抄録
The steroidal D-rings (31 and 37), along with 32 and 38, were synthesized by the use of a part or whole of the carbon units of the isopropyl group of l-abietic acid (1), via oxidation of 18 or 20 with Tl (ONO2)3, or addition reaction of 20 with 1, 1-dichloroethylene, and modifications of the functionality, followed by Friedel-Crafts cyclization. Cyclization to the 14-position (formation of 31 or 37) in 30 or 35 was always predominant over that to the 12-position (formation of 32 or 38). In attempts for functionalization of the isopropyl group with Pb (OAc)4, 9, a hopeful intermediate to syntheseze quinoid diterpenes, was obtained via 3, 4, 5 and 6. RuO2 reduction of 6 and successive Pb (OAc)4 oxidation to 17 is also described.
