Sulfoximine--Titanium Reagents in Enantioselective Trimethylsilylcyanations of Aldehydes.
摘要:
Chiral titanium reagents derived from optically active sulfoximines and Ti(O-i-Pr)(4) promote the asymmetric addition of trimethysilyl cyanide to aldehydes affording cyanohydrins in high yields with good enantioselectivities (up to 91% ee). The ligand structure and the reaction conditions have been optimized. With substoichiometric amounts of the sulfoximine-titanium reagent the product is obtained in decreased yield with lower enantiomeric excess. The molecular structures of (R)-S-(2-hydroxyphenyl)-S-methyl sulfoximine [(R)-4a] and (R)-S-(2-hydroxyphenyl)-S-(1,1-dimethylethyl) sulfoximine [(R)-4d] have been determined by X-ray diffraction analysis.
Sulfoximine--Titanium Reagents in Enantioselective Trimethylsilylcyanations of Aldehydes.
摘要:
Chiral titanium reagents derived from optically active sulfoximines and Ti(O-i-Pr)(4) promote the asymmetric addition of trimethysilyl cyanide to aldehydes affording cyanohydrins in high yields with good enantioselectivities (up to 91% ee). The ligand structure and the reaction conditions have been optimized. With substoichiometric amounts of the sulfoximine-titanium reagent the product is obtained in decreased yield with lower enantiomeric excess. The molecular structures of (R)-S-(2-hydroxyphenyl)-S-methyl sulfoximine [(R)-4a] and (R)-S-(2-hydroxyphenyl)-S-(1,1-dimethylethyl) sulfoximine [(R)-4d] have been determined by X-ray diffraction analysis.
A Mild Synthetic Procedure for the Preparation of N-Alkylated Sulfoximines
作者:Carsten Bolm、Christian P. R. Hackenberger、Oliver Simić、Marinella Verrucci、Dirk Müller、Frank Bienewald
DOI:10.1055/s-2002-28514
日期:——
N-Alkylated sulfoximines have been synthesized in good yields by acylation of NH-sulfoximines followed by carbonyl reduction with complexed boranes. Enantiopure substrates react without racemization, and stereogenic centers originating from the acylating component are retained. If the acylation is performed by DCC coupling, this two-step procedure represents a rare example of a formal N-alkylation of sulfoximines under base-free conditions.
Ethylene-Bridged Bissulfoximines in Copper-Catalyzed Enantioselective Hetero-Diels--Alder Reactions
作者:Carsten Bolm、Marinella Verrucci、Oliver Simic、Christian P. R. Hackenberger
DOI:10.1002/adsc.200505104
日期:2005.10
Ethylene-bridgedbissulfoximines were applied as chiral ligands in copper-catalyzedenantioselective hetero-Diels–Alder reactions. After optimization of the reaction conditions, products with up to 99% ee were obtained.
Sulfoximine--Titanium Reagents in Enantioselective Trimethylsilylcyanations of Aldehydes.
作者:Carsten Bolm、Peter Müller、Klaus Harms、Kim Simonsen、György Liptay、Katrin Trautwein-Fritz、Joseph Stackhouse、Mauro I. Ciglic、Monika Haugg、Nathalie Trabesinger-Rüf、Elmar G. Weinhold
DOI:10.3891/acta.chem.scand.50-0305
日期:——
Chiral titanium reagents derived from optically active sulfoximines and Ti(O-i-Pr)(4) promote the asymmetric addition of trimethysilyl cyanide to aldehydes affording cyanohydrins in high yields with good enantioselectivities (up to 91% ee). The ligand structure and the reaction conditions have been optimized. With substoichiometric amounts of the sulfoximine-titanium reagent the product is obtained in decreased yield with lower enantiomeric excess. The molecular structures of (R)-S-(2-hydroxyphenyl)-S-methyl sulfoximine [(R)-4a] and (R)-S-(2-hydroxyphenyl)-S-(1,1-dimethylethyl) sulfoximine [(R)-4d] have been determined by X-ray diffraction analysis.