Scholars@Duke
Steven W. Baldwin

Steven W. Baldwin

Professor Emeritus of Chemistry
Chemistry
steven.baldwin@duke.edu
Box 90346, Durham, NC 27708-0346
1101 French Science Center, Durham, NC 27708
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Selected Publications

Cationic alkylaluminum-complexed zirconocene hydrides: NMR-spectroscopic identification, crystallographic structure determination, and interconversion with other zirconocene cations

Journal Article Journal of the American Chemical Society · 2011 Featured Publication The ansa-zirconocene complex rac-Me2Si(1-indenyl) 2ZrCl2 ((SBI)ZrCl2) reacts with diisobutylaluminum hydride and trityl tetrakis(perfluorophenyl)borate in hydrocarbon solutions to give the cation [(SBI)Zr(μ-H)3(Al iBu2)2]+, the identity of which is derived ... Full text Cite

Cationic alkylaluminum-complexed zirconocene hydrides as participants in olefin polymerization catalysis

Journal Article Journal of the American Chemical Society · October 13, 2010 The alkylaluminum-complexed zirconocene trihydride cation [(SBI)Zr(μ-H)3(AliBu2)2] +, which is obtained by reaction of (SBI)ZrCl2 with [Ph3C][B(C6F5)4] and excess HAl iBu2 in toluene solution, catalyzes the formation of isotactic polypropene when exposed t ... Full text Cite

Direct, regioselective synthesis of 2,2-dimethyl-2H-chromenes. Total syntheses of octandrenolone and precocenes I and II

Journal Article Tetrahedron Letters · September 9, 2009 Herein is reported an efficient method for the synthesis of 2,2-dimethyl-2H-chromenes in a single step from the corresponding phenol and 3-methyl-2-butenal via microwave irradiation in CDCl3. This protocol features a mild reaction environment (neutral, no ... Full text Cite

Alkylaluminum-complexed zirconocene hydrides: Identification of hydride-bridged species by NMR spectroscopy

Journal Article Journal of the American Chemical Society · December 24, 2008 Reactions of unbridged zirconocene dichlorides, (R nC 5H 5-n) 2ZrCl 2 (n=0, 1, or 2), with diisobutylaluminum hydride (HAI'Bu 2) result in the formation of tetranuclear trihydride clusters of the type (R nC 5H 5-n) 2Zr(μ-H) 3(Al iBu2)3(μ-CI) 2, which conta ... Full text Cite

New spirocyclic oxindole synthesis based on a hetero Claisen rearrangement.

Journal Article Organic letters · July 2004 [reaction: see text] A new method for preparing spirocyclic oxindoles is presented. Featuring a [3,3]-sigmatropic enolate rearrangement, the three-step process converts carboxylic acid starting materials to oxidnole products in overall yields of 52-76%. Th ... Full text Cite

2-tert-butyl-3-methyl-2,3-dihydroimidazol- 4-one-N-oxide: a new nitrone-based chiral glycine equivalent.

Journal Article Organic letters · May 2004 Cycloaddition reactions between a new homochiral imidazolone-derived nitrone afford cycloadducts in high yield and with high stereoselectivity. Subsequent cycloadduct elaboration affords the gamma-lactones of gamma-hydroxy-alpha-amino acids as well as the ... Full text Cite

Synthesis and evaluation of (18)F-labeled choline analogs as oncologic PET tracers.

Journal Article J Nucl Med · December 2001 UNLABELLED: Elevated levels of choline (trimethyl-2-hydroxyethylammonium) and choline kinase (CK) activity in neoplasms have motivated the development of positron-labeled choline analogs for noninvasive detection of cancer using PET. The aim of this study ... Link to item Cite

Enantioselective syntheses of homophenylalanine derivatives via nitrone 1,3-dipolar cycloaddition reactions with styrenes

Journal Article Tetrahedron Letters · August 6, 2001 A new two-step route to derivatives of homophenylalanine is presented. Cycloaddition of a cyclic nitrone glycine template with various styrene derivatives affords good yields of 5-substituted cycloadducts. One-step hydrogenolysis (three bonds) then affords ... Full text Cite

Synthesis and evaluation of 18F-labeled choline as an oncologic tracer for positron emission tomography: initial findings in prostate cancer.

Journal Article Cancer Res · January 1, 2001 The up-regulation of rates of choline uptake and phosphorylation in certain malignancies has motivated the development of positron-labeled choline analogues for noninvasive detection of cancer using positron emission tomography (PET). The choline analogue, ... Link to item Cite

9:30-9:45. Preliminary Evaluation of F-18 Fluorocholine (FCH) as a PET Tumor Imaging Agent.

Journal Article Clin Positron Imaging · July 2000 The purpose of this study was to develop and evaluate an F-18 labeled choline tumor imaging agent.FCH was synthesized through the intermediate F-18 fluorobromomethane that was used to alkylate dimethylethanolamine. The isolated FCH was evaluated in PC-3 hu ... Full text Link to item Cite

A solution to the cyclic aldol problem

Journal Article Organic letters · May 2000 [formula: see text] A protocol for achieving stereoselective aldol reactions with cyclic ketones is presented. In terms of yield, the process is particularly effective when a quaternary center at the alpha-carbon of the beta-hydroxy ketone product is creat ... Full text Cite

Total syntheses of (-)-haemanthidine, (+)-pretazettine, and (+)-tazettine.

Journal Article Organic letters · January 2000 [structures: see text] The total syntheses of the amaryllidaceae alkaloids haemanthidine, pretazettine, and tazettine as optically pure enantiomers are reported. Using D-mannose as the starting material, the critical relative stereochemical relationships a ... Full text Cite

Preparation and evaluation of a cyclic acyl nitrone as a synthon for stereospecific α-amino acid synthesis

Journal Article Tetrahedron Letters · September 17, 1998 The preparation and characterization of cyclic optically active (5R)- 3,4,5,6-tetrahydro-5-phenyl-2H-1,4-oxazin-2-one-N-oxide (2) is described. This nitrone, which is viewed as a template for the synthesis of γ- oxygenated α-amino acids, reacts with alkene ... Full text Cite

Studies Directed at the Synthesis of Optically Active Pretazettine via Intramolecular Nitrone/Alkene Cycloaddition Reactions

Journal Article Journal of Organic Chemistry · November 1, 1991 A protocol for the synthesis of optically active pretazettine which focuses on both the control of relative stereochemistry between the angular aryl and C6a hydroxyl groups and absolute stereochemistry has been developed and executed. The synthesis of the ... Full text Cite

Diastereoselective diels-alder reactions between substituted 1,3-butadienes and n-α-methylbenzylmaleimide

Journal Article Tetrahedron Letters · October 14, 1991 The TiCl4 catalyzed reaction between 2-t-butyl-1,3-butadiene and N-α-methylbenzylmaleimide at -65°C affords diastereomeric Diels-Alder adducts in a 15:1 ratio. The structure of the major adduct was determined by x-ray. © 1991. ... Full text Cite

Stereochemistry of the reactions of some "CH3-" nucleophiles with 2-(tetrahydrofur-2′-yl)-acetaldehyde

Journal Article Tetrahedron Letters · April 22, 1991 The addition of a series of "CH3-" nucleophiles to aldehyde 4 provides selectivities which range from 1/3.5 to 140/1. © 1991. ... Full text Cite

Effect of Nitrogen Substitution on the Diastereoselection of Intramolecular Nitrone/Alkene Cycloadditions

Journal Article Synthetic Communications · February 1, 1991 The diastereomeric ratios of several intramolecular nitrone/alkene cycloaddition reactions have been shown to be sensitive to the substituent on the nitrone nitrogen in a double diastereodifferentiation process. © 1991, Taylor & Francis Group, LLC. All rig ... Full text Cite

Cationic alkylaluminum-complexed zirconocene hydrides: NMR-spectroscopic identification, crystallographic structure determination, and interconversion with other zirconocene cations

Journal Article Journal of the American Chemical Society · 2011 Featured Publication The ansa-zirconocene complex rac-Me2Si(1-indenyl) 2ZrCl2 ((SBI)ZrCl2) reacts with diisobutylaluminum hydride and trityl tetrakis(perfluorophenyl)borate in hydrocarbon solutions to give the cation [(SBI)Zr(μ-H)3(Al iBu2)2]+, the identity of which is derived ... Full text Cite

Cationic alkylaluminum-complexed zirconocene hydrides as participants in olefin polymerization catalysis

Journal Article Journal of the American Chemical Society · October 13, 2010 The alkylaluminum-complexed zirconocene trihydride cation [(SBI)Zr(μ-H)3(AliBu2)2] +, which is obtained by reaction of (SBI)ZrCl2 with [Ph3C][B(C6F5)4] and excess HAl iBu2 in toluene solution, catalyzes the formation of isotactic polypropene when exposed t ... Full text Cite

Direct, regioselective synthesis of 2,2-dimethyl-2H-chromenes. Total syntheses of octandrenolone and precocenes I and II

Journal Article Tetrahedron Letters · September 9, 2009 Herein is reported an efficient method for the synthesis of 2,2-dimethyl-2H-chromenes in a single step from the corresponding phenol and 3-methyl-2-butenal via microwave irradiation in CDCl3. This protocol features a mild reaction environment (neutral, no ... Full text Cite

Alkylaluminum-complexed zirconocene hydrides: Identification of hydride-bridged species by NMR spectroscopy

Journal Article Journal of the American Chemical Society · December 24, 2008 Reactions of unbridged zirconocene dichlorides, (R nC 5H 5-n) 2ZrCl 2 (n=0, 1, or 2), with diisobutylaluminum hydride (HAI'Bu 2) result in the formation of tetranuclear trihydride clusters of the type (R nC 5H 5-n) 2Zr(μ-H) 3(Al iBu2)3(μ-CI) 2, which conta ... Full text Cite

New spirocyclic oxindole synthesis based on a hetero Claisen rearrangement.

Journal Article Organic letters · July 2004 [reaction: see text] A new method for preparing spirocyclic oxindoles is presented. Featuring a [3,3]-sigmatropic enolate rearrangement, the three-step process converts carboxylic acid starting materials to oxidnole products in overall yields of 52-76%. Th ... Full text Cite

2-tert-butyl-3-methyl-2,3-dihydroimidazol- 4-one-N-oxide: a new nitrone-based chiral glycine equivalent.

Journal Article Organic letters · May 2004 Cycloaddition reactions between a new homochiral imidazolone-derived nitrone afford cycloadducts in high yield and with high stereoselectivity. Subsequent cycloadduct elaboration affords the gamma-lactones of gamma-hydroxy-alpha-amino acids as well as the ... Full text Cite

Synthesis and evaluation of (18)F-labeled choline analogs as oncologic PET tracers.

Journal Article J Nucl Med · December 2001 UNLABELLED: Elevated levels of choline (trimethyl-2-hydroxyethylammonium) and choline kinase (CK) activity in neoplasms have motivated the development of positron-labeled choline analogs for noninvasive detection of cancer using PET. The aim of this study ... Link to item Cite

Enantioselective syntheses of homophenylalanine derivatives via nitrone 1,3-dipolar cycloaddition reactions with styrenes

Journal Article Tetrahedron Letters · August 6, 2001 A new two-step route to derivatives of homophenylalanine is presented. Cycloaddition of a cyclic nitrone glycine template with various styrene derivatives affords good yields of 5-substituted cycloadducts. One-step hydrogenolysis (three bonds) then affords ... Full text Cite

Synthesis and evaluation of 18F-labeled choline as an oncologic tracer for positron emission tomography: initial findings in prostate cancer.

Journal Article Cancer Res · January 1, 2001 The up-regulation of rates of choline uptake and phosphorylation in certain malignancies has motivated the development of positron-labeled choline analogues for noninvasive detection of cancer using positron emission tomography (PET). The choline analogue, ... Link to item Cite

9:30-9:45. Preliminary Evaluation of F-18 Fluorocholine (FCH) as a PET Tumor Imaging Agent.

Journal Article Clin Positron Imaging · July 2000 The purpose of this study was to develop and evaluate an F-18 labeled choline tumor imaging agent.FCH was synthesized through the intermediate F-18 fluorobromomethane that was used to alkylate dimethylethanolamine. The isolated FCH was evaluated in PC-3 hu ... Full text Link to item Cite

A solution to the cyclic aldol problem

Journal Article Organic letters · May 2000 [formula: see text] A protocol for achieving stereoselective aldol reactions with cyclic ketones is presented. In terms of yield, the process is particularly effective when a quaternary center at the alpha-carbon of the beta-hydroxy ketone product is creat ... Full text Cite

Total syntheses of (-)-haemanthidine, (+)-pretazettine, and (+)-tazettine.

Journal Article Organic letters · January 2000 [structures: see text] The total syntheses of the amaryllidaceae alkaloids haemanthidine, pretazettine, and tazettine as optically pure enantiomers are reported. Using D-mannose as the starting material, the critical relative stereochemical relationships a ... Full text Cite

Preparation and evaluation of a cyclic acyl nitrone as a synthon for stereospecific α-amino acid synthesis

Journal Article Tetrahedron Letters · September 17, 1998 The preparation and characterization of cyclic optically active (5R)- 3,4,5,6-tetrahydro-5-phenyl-2H-1,4-oxazin-2-one-N-oxide (2) is described. This nitrone, which is viewed as a template for the synthesis of γ- oxygenated α-amino acids, reacts with alkene ... Full text Cite

Studies Directed at the Synthesis of Optically Active Pretazettine via Intramolecular Nitrone/Alkene Cycloaddition Reactions

Journal Article Journal of Organic Chemistry · November 1, 1991 A protocol for the synthesis of optically active pretazettine which focuses on both the control of relative stereochemistry between the angular aryl and C6a hydroxyl groups and absolute stereochemistry has been developed and executed. The synthesis of the ... Full text Cite

Diastereoselective diels-alder reactions between substituted 1,3-butadienes and n-α-methylbenzylmaleimide

Journal Article Tetrahedron Letters · October 14, 1991 The TiCl4 catalyzed reaction between 2-t-butyl-1,3-butadiene and N-α-methylbenzylmaleimide at -65°C affords diastereomeric Diels-Alder adducts in a 15:1 ratio. The structure of the major adduct was determined by x-ray. © 1991. ... Full text Cite

Stereochemistry of the reactions of some "CH3-" nucleophiles with 2-(tetrahydrofur-2′-yl)-acetaldehyde

Journal Article Tetrahedron Letters · April 22, 1991 The addition of a series of "CH3-" nucleophiles to aldehyde 4 provides selectivities which range from 1/3.5 to 140/1. © 1991. ... Full text Cite

Effect of Nitrogen Substitution on the Diastereoselection of Intramolecular Nitrone/Alkene Cycloadditions

Journal Article Synthetic Communications · February 1, 1991 The diastereomeric ratios of several intramolecular nitrone/alkene cycloaddition reactions have been shown to be sensitive to the substituent on the nitrone nitrogen in a double diastereodifferentiation process. © 1991, Taylor & Francis Group, LLC. All rig ... Full text Cite

Nucleophiles with 2-(Tetrahydrofur-2'-γl)-Acetaldehyde

Journal Article Tetrahedron Lett. · 1991 Cite

Stereoselective Synthesis of (±)-methyl Nonactate

Journal Article Journal of Organic Chemistry · January 1, 1987 Racemic methyl nonactate has been prepared in 11 steps from 2,2-dimethyl-3(2H)-furanone with the diastereoisomeric relationships between C-2 and C-3, C-3 and C-6, and C-6 and C-8 established with stereoselectivities of 32:1, 50:1, and 24:1, respectively. © ... Full text Cite

Asymmetric synthesis with chiral hydroxylamines. Synthesis of optically pure 4-substituted azetidinones

Journal Article Tetrahedron Letters · January 1, 1987 The reaction between β-substituted acrylate esters and α-methylbenzyl hydroxyl amine affords diastereoisomeric 5-isoxazolidinones, convenient precursors of simple optically pure 2-azetidinones. © 1987. ... Full text Cite

Face selectivity in the [2+2] photoannelation of chiral 3(2h)-furanones with alkenes

Journal Article Tetrahedron Letters · January 1, 1986 The photocycloadditions of a series of chiral 3(2H)-furanones with alkenes show facial selectivities which parallel the steric bulk of the furanone substituents. Selectivities approaching 50:1 are observed in some instances. © 1986. ... Full text Cite

Total Synthesis of (+)-Elemol by Photoannelation

Journal Article Journal of Organic Chemistry · January 1, 1985 A total synthesis of the monocyclic sesquiterpene elemol has been accomplished in seven steps and 16.7% overall yield. The key new carbon-carbon bonds were formed by the [2 + 2] photochemical cycloaddition reaction between 2,2,6-trimethyl-4H-1,3-dioxin-4-o ... Full text Cite

Total Synthesis of (−)-Sarracenin by Photoannelation

Journal Article Journal of the American Chemical Society · January 1, 1982 Full text Cite

Spiro[4.5]decanes by photoannelation. Total synthesis of (-)-acorenone

Journal Article Tetrahedron Letters · January 1, 1982 An efficient synthesis of the optically active spiro[4.5]decane sesquiterpene acorenone is described. The key carbon-carbon bonds are formed by a (2+2) photochemical cycloaddition between 2,2-dimethyl-3(2H)-furanone and an alkene derived from limonene. © 1 ... Full text Cite

Facile synthesis of 2-substituted cyclopentenones

Journal Article Tetrahedron Letters · January 1, 1982 An efficient synthesis of 2-substituted cyclopentenones is reported. Key reactions are the cylopropanation of 2,2-dimethyl-3(2H)-furanone and subsequent conversion to the title compounds by oxidative fragmentation. © 1982. ... Full text Cite

Total synthesis of d,1-occidentalol by photoannelation

Journal Article Tetrahedron Letters · January 1, 1982 A nine step synthesis of an intermediate previously used in the synthesis of the sesquiterpene occidentalol is reported which incorporates a 2+2 photocycloaddition reaction as the key carbon carbon bond forming step. © 1982. ... Full text Cite

Synthesis of the Alleged Genipic Acid by Photoannelation

Journal Article Journal of the American Chemical Society · January 1, 1980 Full text Cite

Total Synthesis of dl-Cyclosativene by Cationic Olefinic and Acetylenic Cyclizations

Journal Article Journal of Organic Chemistry · January 1, 1980 Racemic cyclosativene has been prepared stereospecifically by two routes each involving intramolecular capture of a homoallylic carbonium ion by a carbon-carbon multiple bond. Diels-Alder reaction between propynal and 2,3-dimethylcyclopentadiene followed b ... Full text Cite

Four-Carbon Photochemical Annelation of Alkenes with 2,2,6-Trimethyl-1,3-dioxolenone

Journal Article Journal of the American Chemical Society · January 1, 1980 Full text Cite

Cyclohexenones by the photoannelation of alkenes with 2,2-dimethyl-3(2H)-furanone

Journal Article Tetrahedron Letters · January 1, 1979 The photoaddition of alkenes to 2,2-dimethyl-3(2H)-furanone affords products which can be efficiently elaborated to cyclohexenones by two different methods. © 1979. ... Full text Cite

Synthesis of the 2-aza-7-oxatricyclo[4.3.2.04,8]undecane nucleus of some gelsemium alkaloids

Journal Article Tetrahedron Letters · January 1, 1979 The preparation of a key tricyclic intermediate for the eventual total synthesis of the alkaloids gelsemicine and gelsedine is described. © 1979. ... Full text Cite

A convenient preparation of α-methylene-d-valerolactones

Journal Article Synthesis (Germany) · March 1, 1978 Full text Cite

Benzyl and Allyl Diazoacetate in One Carbon Ring Expansions of Ketones

Journal Article Synthetic Communications · January 1, 1978 Full text Cite

A facile synthesis of δ-valerolactones by photoannelation

Journal Article Tetrahedron Letters · January 1, 1978 Full text Cite

Preparation of Norcocaine

Journal Article Synthetic Communications · January 1, 1977 Full text Cite

Benzylic Bromination With Bromotrichloromethane

Journal Article Synthetic Communications · January 1, 1976 Full text Cite

Reductive Deoxygenation of Esters with Trichlorosilane

Journal Article Journal of Organic Chemistry · December 1, 1975 Full text Cite

Photoannelations with α-Formyl Ketones. Enol Specificity in the Reaction of Acyclic α-Formyl Ketones with Alkenes

Journal Article Journal of Organic Chemistry · June 1, 1975 The irradiation of several acyclic α-formyl ketones in the presence of alkenes gives rise to photoproducts derived exclusively from that tautomer enolized toward the aldehyde carbonyl, which can then be cyclized to provide a new cyclohexenone annelation se ... Full text Cite

Model Studies for the Synthesis of Tetracyclic Sesquiterpenes

Journal Article Synthetic Commun. · 1975 Cite

Model Studies For The Synthesis Of Tetracyclic Sesquiterpenes

Journal Article Synthetic Communications · January 1, 1975 Full text Cite

Stereoselective Synthesis of 3-Exo-Substituted 2-endo-Acyl-5-norborene Derivatives

Journal Article Journal of Organic Chemistry · August 1, 1974 The stereoselective addition of a variety of nucleophiles (ROH, RSH) to several 2-acylnorbornadienes provides an efficient synthesis of the title compounds. The allyl ethers derived from the addition of allyl alcohol are stable to many synthetic transforma ... Full text Cite

Selectivity in the Free-Radical Reduction of Lactones with Trichlorosilane

Journal Article Journal of Organic Chemistry · August 1, 1974 Each of the generally recognized methods for converting lactones to cyclic ethers suffers from distinct structural limitations. For instance, Adams catalyst in an acidic medium will reduce δ-lactones to the corresponding ethers but fails completely with γ- ... Full text Cite

Remote oxidation of steroids by photolysis of attached benzophenone groups.

Journal Article Journal of the American Chemical Society · May 1973 Full text Cite

Intramolecular keten cycloadditions in unconstrained systems

Journal Article Journal of the Chemical Society, Chemical Communications · December 1, 1972 The feasibility of intramolecular keten cycloadditions in acyclic systems is demonstrated; these results implicate keten intermediates in the formation of the cyclobutanone (5) from the cyclohexanone (1). ... Full text Cite

Experiments Directed toward the Total Synthesis of Terpenes. XVII. Development of Methods for the Synthesis of Pentacyclic Triterpenes Based on a Mechanistic Interpretation of the Stereochemical Outcome of the Friedel–Crafts Cyclialkylation Reaction

Journal Article Journal of the American Chemical Society · March 1, 1972 The α-methylene ketone 11 was prepared and found to undergo conjugate addition with m-methoxybenzylmagnesium chloride with great facility. The initial adduct was trapped with acetic anhydride, and the resulting enol acetate 12 was used either in methylatio ... Full text Cite

The Total Synthesis of an Unsymmetrical Pentacyclic Triterpene. DL-Germanicol

Journal Article Journal of the American Chemical Society · September 1, 1970 Full text Cite

Conversion of Cholestanol to 12-Ketocholestanol and to Δ14- and Δ8(14)-Cholestenol by Remote Oxidation

Journal Article Journal of the American Chemical Society · February 1, 1970 Full text Cite

Pyrolysis of 2-Acetoxy-2-(3-oxobutyl)cyclohexane-1,3-dione

Journal Article Journal of Organic Chemistry · April 1, 1965 Full text Cite

Condensation of Diethyl Malonate with Methyl Vinyl Ketone

Journal Article Journal of Organic Chemistry · April 1, 1964 Ethoxide-catalyzed reaction of diethyl malonate with methyl vinyl ketone yields 1-carboxy-6-methylbicyclo-[3.3.1]non-6-ene-2,4-dione (VI) and, after hydrolysis, 1-methyl-2-acetyl-4-carboxycyclohexene-1 (XI). The separately prepared mono-Michael adduct (V) ... Full text Cite