BORANES IN SYNTHESIS .6. A NEW SYNTHESIS OF BETA-AMINO ALCOHOLS FROM EPOXIDES - USE OF LITHIUM AMIDES AND AMINOBORANE CATALYSTS TO SYNTHESIZE BETA-AMINO ALCOHOLS FROM TERMINAL AND INTERNAL EPOXIDES IN HIGH-YIELD

A study of the conversion of terminal and internal epoxides to the corresponding beta-amino alcohols using simple primary and secondary lithium amides has been carried out. Thus, styrene oxide and 1,2-epoxydodecane react directly with primary and secondary lithium amides in THF at 25 degrees C to give a single regioisomer of the corresponding beta-amino alcohols in 80-100% isolated yields. Since internal epoxides are known to yield predominantly allylic alcohols when reacted with lithium amides, we employed a series of aminoborane Lewis-acid catalysts, generated in situ, to suppress formation of the allylic alcohols. Thus, the reaction of cyclohexene oxide with a variety of primary and secondary lithium amides at 34 degrees C in diethyl ether in the presence of a catalytic amount of B-bromo-9-BBN afforded the corresponding beta-amino alcohols in 70-95% isolated yield.