Nonracemic homopropargylic alcohols via asymmetric allenylboration with the robust and versatile 10-TMS-9-borabicyclo[3.3.2]decanes.
The asymmetric allenylboration of representative aldehydes with the stable, storable 1 is reported. Easily and efficiently prepared in either enantiomeric form from the air-stable crystalline 4 through simple Grignard procedures, 1 gives 6 cleanly. The latter is easily isolated in high yield and ee with predictable stereochemistry. The procedure also regenerates 4 for its direct conversion back to 1 and facilitates the efficient recovery of the pseudoephedrine. The net process is the synthetic equivalent of the asymmetric addition of allenylmagnesium bromide to aldehydes. [reaction: see text]
Lai
Chunqiu
C
Department of Chemistry, University of Puerto Rico, Rio Piedras, Puerto Rico 00931-3346.
Soderquist
John A
JA
D000438:Alcohols / Q000138:chemical synthesis*; D000447:Aldehydes / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry*; D001880:Boranes / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D004809:Ephedrine / Q000138:chemical synthesis; D007202:Indicators and Reagents
D000438:Alcohols; D000447:Aldehydes; D000473:Alkanes; D001880:Boranes; D007202:Indicators and Reagents; D004809:Ephedrine; C012867:decane