A Novel Method To Generate Chiral Quaternary Carbon Centers of High Enantiomeric Purity Using a Highly Stereoselective Addition of Vinylalanes to a Chiral Aldehyde

Abstract

The anti addition of cyanocuprates to chiral pivalates 2 derived from aldehyde 1 generates aldehydes 3 with a chiral quaternary carbon center. The generation of the alcohol precursors was achieved by a highly stereoselective addition of vinylalanes on the aldehyde auxiliary. Piv=pivaloyl=2,2‐dimethylpropyl.

Catalytic Enantioselective Synthesis of Trisubstituted Secondary Allylic Alcohols Starting from Terminal Alkynes and Aldehydes

“…Despite their accessibility, these vinylaluminium reagents are highly reactive towards carbonyl groups, undergoing addition reactions even at low temperatures without the aid of a catalyst 11. Thus, for the catalytic enantioselective carbonyl addition of these vinlyaluminium reagents to be successful, a catalytic system with not only a high enantioselectivity, but also with a high turnover frequency is necessary, to overwhelm a noncatalytic background reaction leading to a racemic product.…”

Enantioselective synthesis of all-carbon quaternary stereogenic centers in acyclic systems

“…Spino and Beaulieu have demonstrated the versatility of p-menthane-3-carboxaldehyde as a chiral auxiliary to prepare compounds containing a chiral quaternary center of high enantiomeric ratio. 4 Diastereomerically pure starting materials react with a range of alkyl cuprates R 2 CuCNMgBr, using Goering's procedure, 5 to give the addition products in good yields and with excellent stereoselectivities (up to 99/1 dr) (Scheme 2).…”

Menthone and p-menthyl-3-carboxaldehyde as chiral auxiliaries

“…Against my own advice, 28 Christian Beaulieu added p-menthyl-3-carboxaldehyde 41 directly to the mixture obtained from the carboalumination of n-hexyne (45a, R 1 = n-Bu) and procured 80% yield of the corresponding two alcohols 46a and 47a (R 1 = n-Bu, R 2 = Me) in a 20 : 1 ratio. 29 The major product 46a was the result of a Felkin-Anh addition to aldehyde 41 (Scheme 9).…”