Enantioselective synthesis of 2-methyl-1,2-syn- and 2-methyl-1,2-anti-3-butenediols via allene hydroboration-aldehyde allylboration reaction sequences.

ABSTRACT: The hydroboration of allene 7 with ((d)Ipc)(2)BH at 0 degrees C provides the kinetic allylborane 12Z with >20:1 selectivity. However, when the hydroboration is performed at 85 degrees C, the kinetically formed allylborane isomerizes to give the thermodynamic allylborane 12E with >or=12:1 selectivity. Subsequent treatment of 12Z or 12E with aldehydes at -78 degrees C, followed by oxidative workup, provides the 2-methyl-1,2-diols 8 and 9 in good yield and with 80-92% e.e.

SUBMITTER: Chen M 

PROVIDER: S-EPMC2762002 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature