An enantiodivergent synthesis of N-Boc-protected (R)- and (S)-4-amino cyclopent-2-en-1-one

Routes are reported for the synthesis of both (1 R)- and (1 S)- tert-butyl-(4-oxocyclopent-2-en-1-yl)carbamate 2. Featuring Mitsunobu reactions with di- tert-butyl iminodicarbonate, both syntheses begin from ( S)-4-[( tert-butyldimethylsilyl)oxy]cyclopent-2-en-1-one (3) and take advantage of the 1,4-cyclopentenyl dioxygenation pattern of this optically active starting material. Thus both (−)- and (+)-2 have been accessed from 3 in an enantiodivergent manner in 11% and 10% overall yield over five and seven reaction steps, respectively.