APPROACHES TO THE SYNTHESIS OF CYTOCHALASANS .9. 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 LiCuPh2 was not successful. But treatment of the N‐protected model lactams 19, 21, and 22 with Li2Cu(CN)Ph2 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. Copyright © 1990 Verlag GmbH & Co. KGaA, Weinheim