Approaches to the Synthesis of Cytochalasans Part9 . A versatile concept leading to all structural types of cytochalasans

Starting from D‐glutamic acid ( 5 ), the bicyclic compounds 4a and 4b were synthesized via 17 ( Schemes 1 and 2 ). The reaction leading to 4g and 4h with LiCuPh 2 was not successful. But treatment of the N‐protected model lactams 19 , 21 , and 22 with Li 2 Cu(CN)Ph 2 gave the amino ketones 24 , 26 , and 27 , respectively ( Scheme 3 ). The desired compound 23 was obtained from 20. Conversion of the unprotected lactams 28 , 31 , and 32 gave the phenyl derivative 34 in excellent yields. Ester 35 was transformed to the α ‐amino‐γ‐ oxo‐acid derivative 36. This conversion opens a novel access to this type of compounds.