Enantioselective synthesis of α-branched α-hydroxy ketones via chiral N-sulfonyl-2-alkyl-2-cyano-1,3-oxazolidines

Mild Electrochemical Deprotection of N‐Phenylsulfonyl N‐Substituted Amines Derived from (R)‐Phenylglycinol

“…Nevertheless, to the best of our knowledge these studies were mostly limited to unfunctionalized sulfonamides,24 even if desulfonylation by electrochemical reduction was used in some multistep syntheses 32,33. In connection with some ongoing projects, we were interested in the smooth and selective removal of the arenesulfonyl group on β‐amino alcohols that was compatible with functionalities, stereogenic centres and nitrogen substitution 34.…”

Highly Regioselective, Catalytic Asymmetric Reductive Coupling of 1,3-Enynes and Ketones

“…25 Ozonolysis of these compounds affords R-hydroxy ketones such as 15, the TMS ether of which has been employed by Masamune in asymmetric aldol reactions. 26 This two-step procedure also allowed assignment of the configuration of the major enantiomer of dienol 5 as S. 27 In summary, we have developed the first catalytic asymmetric reductive coupling of alkynes and ketones, a transformation in which 1,3-enynes are uniquely effective substrates. This transformation is highly regioselective and affords synthetically useful 1,3-dienes with an adjacent quaternary carbinol stereogenic center in moderate enantioselectivity.…”

“…Ozonolysis of these compounds affords α-hydroxy ketones such as 15 , the TMS ether of which has been employed by Masamune in asymmetric aldol reactions . This two-step procedure also allowed assignment of the configuration of the major enantiomer of dienol 5 as S 2 …”

The Use of N‐Boc‐1,3‐Oxazolidines as Chiral Auxiliaries in Asymmetric Synthesis

“…Hoppe next described an electrochemical cleavage of the Ntosyloxazolidine, which allowed access to an optically enriched α-hydroxy ketone by this methodology. [28] It should be noted that the stereoselective reduction of an ephedrinederived N-tosyl-2-acetyloxazolidine of 2,4-cis stereochemistry had previously been studied and optimized by Scolastico, [29] but the synthesis of this ketone was indirect, since it involved the oxidative cleavage of an intermediate alkenyloxazolidine. Furthermore, the transthioacetalisation described above, intended to unmask the aldehyde, failed to produce the α-hydroxythioacetal.…”