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 °C while reaction with (EtO)2PO-/(EtO)2P(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 adducts are postulated as intermediates. Reactions of PhCH=C(R)NO2 (R = H, Me, Ph) with (EtO)3P at 150 °C or (EtO)2PO-/(EtO)2P(O)H at room temperature give products resulting from the addition of the phosphorus nucleophile at the benzylidene carbon atom. Evidence for the formartion of cyclic structures with pentacoordinated phosphorus atoms is presented for the reaction of Ph2C=C(Me)NO2 with (EtO)2PO-/EtO)2P(O)H and for PhCH=C(R)NO2 (R = H, Me, Ph) with (EtO)O3P. The Michael-type adducts PhCH[P(O)(OEt)2]CH(R)NO2 (R = Me, Ph) undergo reaction upon treatment with aqueous base at 80–100 °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 85% H2SO4 of the adducts of PhCH=C(R)NO2 with (EtO)2PO- (R = Me) or (EtO)3P (R = Ph).
ASJC Scopus subject areas
- Organic Chemistry