Stereoselective reduction of 2- or 3-substituted 4-piperidones w

Details Stereoselective reduction of 2- or 3-substituted 4-piperidones w Stereoselective reduction of 2- or 3-substituted 4-piperidones w

1983-03-14

1985-01-29

Milestone, Norma S.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

546242, C07D21146

Patent

active

044967322

ABSTRACT:
A stereoselective reduction of 2- or 3-substituted 4-piperidones of the formula ##STR1## where R.sub.1 is hydrogen, loweralkyl or benzyl and R.sub.2 is methyl or ethyl, to the di-equatorial isomer of the corresponding 4-piperidinol is described. Said reduction is conducted by use of sodium borohydride in a protic solvent medium at a temperature substantially lower than ambient temperature in the presence of an effective amount of an inorganic acid. Under favorable reaction conditions, the stereoselectivity of the reduction is so high that simple crystallization of the reaction product affords the pure isomer in a commercially acceptable and advantageous process.

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