Reformatsky-Type Reaction of Chiral Nonracemic α-Bromo-α‘-sulfinyl Ketones with Aldehydes. Synthesis of Enantiomerically Pure 2-Methyl-1,3-diol Moieties

Abstract

Chiral nonracemic alpha-bromo-alpha'-sulfinyl ketones were shown to react with aldehydes in the presence of SmI(2) in a Reformatsky-type reaction to give the corresponding adduct with excellent syn diastereoselectivity. Further reduction of the Reformatsky adducts furnished anti- and syn-2-methyl-1,3-diol moieties in excellent yields and diastereoselectivities.

Recent developments in chiral non-racemic sulfinyl group chemistry in asymmetric synthesis

“…63 The key-step of this method is a stereoselective samarium-promoted Reformatsky reaction with linear aliphatic aldehydes. When the sulfur atom is substituted by a tert-butyl group high 1,4 induction with a strong syn-selectivity is observed (de>90%) (Scheme 32).…”

A New Access to Enantiopure syn‐ and anti‐2‐Methyl‐1,3‐diol Moieties from Chiral Nonracemic α‐Bromo α′‐Sulfinyl Ketones Promoted by Samarium Diiodide

“…Up to 96 % syn diastereomeric excess was obtained with linear aldehydes. [6] Further reduction of the Reformatsky adducts furnished anti-and syn .…”

DMAP‐Catalysed Sulfinylation of Diacetone‐D‐Glucose: Improved Method for the Synthesis of Enantiopure tert‐Butyl Sulfoxides and tert‐Butanesulfinamides

“…Condensation of the Grignard reagent derived from 3‐bromoanisole with enantiopure ( R S )‐diacetone‐ D ‐glucose tert ‐butanesulfinate gave the corresponding enantiopure sulfoxide (i.e., 12 S S ) in 82 % yield. Compound 12 S S is an excellent intermediate for the synthesis of diastereomerically pure axially chiral biaryl compounds by Pd‐catalysed Suzuki–Miyaura cross‐coupling 17. In the same way, the reaction of a benzyl Grignard reagent with ( R S )‐diacetone‐ D ‐glucose tert ‐butanesulfinate led to benzyl tert ‐butyl sulfoxide ( 13 S S )36 with no loss in enantiopurity, as shown by HPLC analysis.…”

“…Pioneering work from Casey's group has shown the superiority of the tert ‐butyl sulfoxide over the p ‐tolyl sulfoxide in Michael additions 12. The same trend was reported in the synthesis of chiral amines,13 in the aziridination of sulfinylimine,14 in the Pauson–Khand reaction,15 in the Cu‐catalysed Diels–Alder reaction,16 in the Reformatsky reaction,17 in Suzuki–Miyaura cross‐coupling,18 and in the Rh‐catalysed addition of boronic acids to activated ketones 19. This has spurred the search for new and more hindered sulfinylating agents in general, and tert ‐butanesulfinylating agents in particular.…”