Insect Moulting Hormones. LV. Experiments Directed Towards the Synthesis of Non-steroidal Ecdysone Analogues

Abstract

Exploratory studies aimed at the synthesis of the non-steroidal ecdysone analogue (4aR,7S,8aR,-1′RS,4′R)-7-hydroxy-3-(1′-hydroxy-4′,8′- dimethylnonyl )-4a-methyl-4a,5,6,7,8,8a-hexahydronaphthal-en- 1(4H)-one (3) have led to in efficient method of joining the cyclic and side-chain synthons by reacting the vinylogous ester (4a) with 1-lithio-4,8-dimethyl-1,1-bis( methylthio ) nonane (12) to yield (4′RS)-3- [4′,8′-dimethyl-1′,1′-bis( methylthio ) nonyl ]-5,5-dimethylcyclohex-2-en-1-one (13). This thioacetal on reaction with boron trifluoride etherate and mercuric oxide afforded, quantitatively, the diketone (4′RS)-3-(4′,8′-dimethyl-1′-oxononyl)-5,5-dimethylcyclohex-2-en-1-one (14) which was selectively reduced in 85% yield to the required model compound (4′RS)-3-(1′-hydroxy-4′,8′-dimethylnonyl)-5,5-dimethylcyclohex-2-en-1-one (15).