128806-22-4

Upstream product

• 104-53-0 3-phenyl-propionaldehyde 
• 63584-47-4 (1-tert-butylsulfanyl-vinyloxy)trimethylsilane 
• 999-90-6 S-tert-butyl thioacetate 

Relevant academic research and scientific papers

Optimisation, scope and limitations of enantioselective aldol reactions of an S-ketene silyl acetal with aliphatic aldehydes under (R)-BINOL-titanium(IV) catalysis conditions

The Mukaiyama aldol reaction between the functionalised aldehydes 5 and the S-ketene silyl acetal 2 catalysed by 1,1'-binaphthyl-derived chiral titanium(IV) complex 4 afforded the corresponding aldol products 6 in good yields and with good to excellent enantioselectivities. The chemical yield could further be enhanced, without loss of stereoselection, by addition of phenol and/or molecular sieves. The presented aldol reactions with aluminium, boron and ytterbium-BINOL catalysts demonstrate that only low chiral induction can be achieved. Aldol product 6a was converted into an α-lipoic acid precursor 8, thus providing a formal synthesis of this biologically active compound. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).

Asymmetric Synthesis of Functionalized Secondary Alcohols by Catalytic Ring-Cleavage Reactions of Cyclic Acetals Derived from (R)-1,3-Butanediol

In the presence of a catalytic amount (0.1-0.2 molar amount) of a 2-phenyl-1,3,2-oxazaborolidin-5-one, prepared by the reaction of dichlorophenylborane and N-(trifluoromethylsulfonyl)-L- phenylalanine, and enol silyl ethers ((R2)2C=C-(R3)OTMS; R3 = t-BuS, EtS, EtO, Ph) (1.1-1.5 molar amount), chiral cyclic acetals 6 derived from (R)-1,3-butanediol and aldehydes undergo an efficient ring-cleavage reaction with the inversion of the stereochemistry at the acetal carbon to give the anti isomer of the corresponding products with high stereoselectivity. The reaction is applicable to acetals derived from aromatic, aliphatic, and α,β-unsaturated aldehydes. Not only enol silyl ethers, but also methallyltrimethylsilane and allyltributyltin, can be employed as nucleophiles, leading to the selective formation of the anti isomer of the corresponding allylated ring-cleavage products. Removal of the chiral auxiliary from these ring-cleavage products by a two-step sequence ((i) PCC (ii) Bn2NH2(CF3CO2)) furnishes enantiomerically enriched β-hydroxy carbonyl compounds and homoallyl alcohols. A modest level of kinetic resolution is observed in the ring cleavage of a racemic acetal catalyzed by a phenylboron compound derived from N-mesyl-L-phenylalanine.

The catalytic asymmetric aldol reaction of aldehydes with unsubstituted and monosubstituted silyl ketene acetals: Formation of anti-β-hydroxy-α-methyl esters

The title rection with unsubstituted and monosubstituted silyl ketene acetals proceeds with high enantioselectivity, and in the latter case good diastereoselectivity favoring the anti-β-hydroxy-α-methyl esters in all reported cases.

Asymmetric Aldol Reaction between Achiral Silyl Enol Ethers and Achiral Aldehydes by Use of a Chiral Promoter System

In the presence of a chiral promoter consisting of tin(II) triflate, a chiral diamine, and tributyltin fluoride, the silyl enol ether of S-ethyl ethanethioate or S-tert-butyl ethanethioate reacts with aldehydes to afford the corresponding aldol-type adduc