1 α-アミノ酸から光学活性Carene骨格の合成研究 : (+)-Car-2-eneの合成

抄録

For a total synthesis of the optically active carene derivatives from optically active α-amino acids, several attempts were made on intramolecular cyclization of 2-cyclohexenyl esters of α-substituted-α-diazo acetic acid (3) which were derived from diazotization of the corresponding amino acid esters. Results of model reactions are shown in Table II. One of the optically active diastereoisomers (12) which was obtained by resolution of 2-cyclohexenyl-L-alaninate was diazotized by treatment with isoamylnitrite and then cyclized using Cu powder as a catalyst to afford the optically active lactone (15). (15) was then converted into the key intermediate (17) having the bicyclo[4.1.0] heptane ring system, from which (+)-car-2-ene was synthesized via the sequence, (17)→(18)→(19)→(20)→(21)→(22)→(23)→(+)-car-2-ene.