Reactions of excess RS- (R = Ph, t-Bu) with Ph2C=C(SPh)NO2 in Me2SO form Ph2C=CHSR via conversion of the initial Michael-type adducts into Ph2C(SR)CH=NO2- and Ph2C=CHNO2. In a similar fashion, reaction of (EtO)2PO- with Ph2C=C(SPh)NO2 forms initially mainly PhSP(O)(OEt)2 and PH2C[P(O)(OEt)2]CH=NO2-, which upon acidic workup will yield the nitroalkane or the Nef reaction product, Ph2C[P(O)(OEt)2]CHO. The reaction of (EtO)2PO- with Ph2C=C(SPh)NO2 also produces Ph2C[P(O)(OEt)2]Cs≡N via a Perkow-type reaction of the Michael adduct to yield Ph2C[P(O)(OEt)2]CH=N(O)OP(O)(OEt)2 as an intermediate. The nitrile is also formed from Ph2C[P(O)(OEt)2]CH(NO2)2 with (EtO)2PO- in (EtO)2P(O)H or Me2O at 30 °C and in >95% yield by the reaction of (EtO)3P with Ph2C[P(O)(OEt)2CH(NO2)2 at 150 °C. Reaction of Ph2C=CHNO2 or Ph2C-[P(O)(OEt)2]CH2NO2 with excess (EtO)2PO- in Me2SO or (EtO)2P(O)H forms 3-(diethoxyphosphinyl)-2,2-diphenylaziridine by a process postulated to involve Ph2C=CHN(O-)OP(O)(OEt)2, Ph2C=CHNOP(O)(OEt)2; and 2, 2-diphenyl-2H-azirine. Similarly, Ph2C=C(SBu-t)NO2 and (EtO)2PO- give 3-(tert-butylthio)-2,2-diphenyl-2H-azirine in Me2SO or 2-(tert-butylthio)-3-phenylindole in (EtO)2P(O)H solution. Deoxygenation of Ph2C=C(X)NO2 to form the 2-X-3-phenylindoles occurs in high yield at 150 °C in (EtO)3P with X = H, PhS, or t-BuS while 2-nitro-3-phenylindole is formed from Ph2C=C(NO2)2 in (EtO)2P(O)H at 150 °C.
ASJC Scopus subject areas
- Organic Chemistry