Asymmetric Sulfinylations ofN‐Methylephedrine‐Modified Tri‐ or Tetraalkyl Zincates by Symmetric Diaryl Sulfoxides

Abstract

Diethylzinc was treated with 1 or 2 equiv. of AlkMgCl or PhMgBr (preferably) or with 1 equiv. of nBuLi (less efficiently) for forming species – plausibly zincates – which were sulfinylated by diaryl sulfoxides to give racemic alkyl aryl sulfoxides in yields reaching 100 %. Dialkylzinc reagents were also activated by treatments with 1 or 2 equiv. of an enantiomerically pure alkylmagnesium β‐aminoalkoxide. This worked best when the alkoxide stemmed from a dialkylmagnesium reagent and an equimolar amount of N‐methyl‐(–)‐ephedrine. This second activation mode allowed sulfinylations of what was originally the dialkylzinc reagent with diaryl sulfoxides. This generated alkyl aryl sulfoxides with enantiomeric ratios up to 93:7 in up to 100 % yield.

Enantioenriched BoronC,N‐Chelates via Chirality Transfer

“…>98 : 2 with boron in the ( R ) B ‐configuration (Scheme 4, top). Additionally, we performed N ‐methylation [59] of the acyclic aminoalcohols and the respective chelates 16 e – g were obtained in 54–86 % and d.r. 93 : 7 ( 16 g ) or up to >98 : 2 ( 16 e,f ) (Scheme 3, middle).…”

“…Additional references cited in the Supporting Information. [9,20,25,42,59,[65][66][67][68][69][70][71][72][73][74][75][76][77] Deposition Numbers 2249555 (for 16 e), 2235885 (for 16 i) and 2235887 (for 18 a) contain the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service.…”