e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
A new stereoselective synthesis of (20 R)-and (20 S)-steroidal side chains
T Ibuka, T Taga, S Nishii, Y Yamamoto
Index: Ibuka, Toshiro; Taga, Tooru; Nishii, Shinji; Yamamoto, Yoshinori Journal of the Chemical Society, Chemical Communications, 1988 , # 5 p. 342 - 344
Reaction of (E)-ethyl 3β-t-butyldimethylsiloxypregna-5, 17-dien-21-oate with lithium di- isopropylamide followed by alkyl halides results in the predominant formation of (20S)- alkylation products in> 88% isolated yields; a synthetic application to both (20R)-and (20S)- steroidal side chains is also described.
![(S)-2-((3S,8R,9S,10R,13S,14S)-3-((tert-butyldimethylsilyl)oxy)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15-dodecahydro-1H-cyclopenta[a]phenanthren-17-yl)propyl 4-methylbenzenesulfonate Structure](https://image.chemsrc.com/caspic/197/115019-42-6.png)
