Reactions of Ethyl phosphites with β-Nitrostyrenes. The Role of Nitrosoalkenes as Intermediates

Article abstract of DOI:10.1021/jo00050a026

3-Phenyl-2-substituted-indoles are formed in high yields in the reaction of Ph2C=C(R)NO2 (R = H, Me, Ph) with (EtO)3P at 150 deg C while reaction with (EtO)2PO(1-)/(Et2O)P(O)H at room temperature forms the aziridines 1 with R = H, Me, Ph. 2,2-Diphenyl-3-substituted-2H-azirines formed by deoxygenation of the Michael-type aducts are postulated as intermediates.Reactions of PhCH=C(R)NO2 (R = H, Me, Ph) with (EtO)3P at 150 deg C or (EtO)2PO(1-)/(EtO)2P(O)H at room temperature give products resulting from the addition of the phosphorus nucleophile at the benzylidene carbonatom.Evidence for the formation of cyclic structures with pentacoordinated phosphorus atoms is presented for the reaction of Ph2C=C(Me)NO2 with (EtO)2PO(1-)/(EtO)2P(O)H and for PhCH=C(R)NO2 (R = H, Me, Ph) with (EtO)3P.The Michael-type adducts PhCHCH(R)NO2 (R = Me, Ph) undergo reaction upon treatment with aqueous base at 80-100 deg C followed by acidification to yield the 3-(diethoxyphosphinyl)-2-R-N-hydroxyindoles. 4-(Diethoxyphosphinyl)-3-R-4H-1,2-benzoxazines (13, R = Me, Ph) are formed by reaction with 85percent H2SO4 of the adducts of PhCH=C(R)NO2 with (EtO)2PO(1-) (R = Me) or (EtO)3P (R = Ph).