The recently discovered reaction between tri-phenylphosphine-alkylidenes of type I11 (obtained from the bromides I by the sequence shown) and carbonyl compounds to produce the corresponding ethylenes IV, the so-called Wittig reaction, has become one of wide scope and utility in synthetic chemistry. 2 We first became interested in the application of this reaction in the steroid field in
![(8R,9S,10R,13S,14S,17S)-3,10,13-trimethyl-2,7,8,9,11,12,14,15,16,17-decahydro-1H-cyclopenta[a]phenanthren-17-ol结构式](https://image.chemsrc.com/caspic/420/60397-35-5.png)
