Deoxygenation reactions of 1-alkenyl nitro compounds with ethyl phosphites and alkylmercury iodides: promotion of reactions of tertiary-butylmercury halides with [alpha],[beta]-unsaturated nitriles in the presence of proton donors

摘要

The mechanism of the reactions of Ph[subscript]2C=C(SPh)NO[subscript]2 with PhS[superscript]-, t-BuS[superscript]- and (EtO)[subscript]2PO[superscript]- in Me[subscript]2SO to form Ph[subscript]2C=CHSPh, Ph[subscript]2C=CHSBu-t and Ph[subscript]2C[P(O)(OEt)[subscript]2] CH[subscript]2NO[subscript]2 has been identified as involving nucleophilic attack upon sulfur in the initially-formed Michael-type adducts. A variety of products from the reaction of Ph[subscript]2C=C(Y)NO[subscript]2 (Y = H, CH[subscript]3, SPh, SBu-t, NO[subscript]2) with excess (EtO)[subscript]2PO[superscript]- is described. Competition is observed between a Perkow-type reaction of the Michael-type adduct (leading to Ph[subscript]2C[P(O)(OEt)[subscript]2] CN) and deoxygenation of Ph[subscript]2C=C(Y)NO[subscript]2 to yield Ph[subscript]2C=C(Y)NO[subscript]2 which reacts further with (EtO)[subscript]2PO[superscript]- to form a 2,2-diphenyl-3-Y-2H-azirine which subsequently rearranges to the 3-phenyl-2-Y-indole. Reactions of Ph[subscript]2C=C(Y)NO[subscript]2 (Y = H, CH[subscript]3, SPh, SBu-t) and PhCH=C(Y)NO[subscript]2, (Y = H, Ph), with t-BuHgI/KI/h[nu] in Me[subscript]2SO are reported. The reactions are postulated to proceed via the formation of RN(OHgI)OBu-t, RN=O and RN(HgCl)OBu-t except for PhCH=CHNO[subscript]2, where t-Bu· addition leads to PhCH=CHBu-t· Among the final reaction products isolated from the appropiate nitroalkene were (t-BuON(O)=C(Ph)-CH(Ph)-) -2 and PhCH[subscript]2(Ph)=NOBu-t, Ph[subscript]2C(OBu-t)CH=NOH, Ph[subscript]2C(OBu-t)C(CH[subscript]3)=NON=C(CH[subscript]3)C(OBu-t)Ph[subscript]2, 2,2-diphenyl-3-phenylthiyl-2H-azirine, 3-phenyl-2-phenylthiylindole and 2-t-butyl-3-phenylindole. The azirine and indoles are presumed to be formed from the intermediate Ph[subscript]2C=C(SR)N(HgCl)OBu-t. With ArNO and t-BuHgI/KI the reaction compounds are mainly the azoxy compound formed by the condensation of ArNO with ArN(HgI)OBu-t (Ar = Ph, o-MeC[subscript]6H[subscript]4). Nitroaromatics are reduced by t-BuHgI/KI/h[nu] presumably via ArN(OHgI)OBu-t and ArNO to yield mainly products of t-Bu· addition to ArNO (ArN(Bu-t)OH, ArN(Bu-t)OBu-t) although azoxy compounds are also produced and in some cases ArNHBu-t is observed, presumably from the conversion of ArN(HgI)OBu-t to ArN: and ArN(HgI)Bu-t;The reaction of [alpha],[beta]-unsaturated nitriles and dinitriles with t-BuHgI/KI/h[nu] to give reductive tert-butylation products are promoted by PTSA, presumably because of the formation of t-BuCH[subscript]2CH=C=NH+, which is readily reduced by t-BuHgI[subscript]2[superscript]-. Promation of reductive tert-butylation was also observed for 2-(1-alkenyl)-4,4,6-trimethyl-5,6-dihydro-1,3-oxazines.