Addition, Substitution, and Deoxygenation Reactions of α-Phenyl-β-nitrostyrenes with the Anions of Thiols and Diethyl Phosphite: Formation of Indoles by Reaction with Ethyl Phosphites

Article abstract of DOI:10.1021/jo00002a032

Reaction 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 Ph2CCH=NO2^-, which upon acidic workup will yield the nitroalkane or the Nef reaction product, Ph2CCHO.The reaction of (EtO)2PO^- with Ph2C=C(SPh)NO2 also produces Ph2CCN via a Perkow-type reaction of the Michael adduct to yield Ph2CCH=N(O)OP(O)(OEt)2 as an intermediate.The nitrile is also formed from Ph2CCH(NO2)2 with (EtO)2PO^- in (EtO)2P(O)H or Me2SO at 30 deg C and in >95percent yield by the reaction of (EtO)3P with Ph2CCH(NO2)2 at 150 deg C.Reaction of Ph2C=CHNO2 or Ph2CCH2NO2 with excess (EtO)PO^- 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 deg C in (EtO)3P with X=H, PhS, or t-BuS while 2-nitrro-3-phenylindole is formed from Ph2C=C(NO2)2 in (EtO)2P(O)H at 150 deg C.