SYNTHESIS OF POLYFUNCTIONALIZED 1-AMINOBUTA-1,3-DIENES BY ADDITION OFDIMETHYL ACETYLENEDICARBOXYLATE TO (Z)-BETA-ENAMINO-LAMBDA(5)-PHOSPHAZENES - CONFIGURATIONAL AND CONFORMATIONAL-ANALYSIS BASED ON NOE DATA,(ETA)J(PX) COUPLING-CONSTANT, X-RAY STRUCTURES, AND SEMIEMPIRICAL CALCULATIONS

DMAD adds regioselectivelly to N-acyl-(Z)-beta-enaminophosphazenes thr ough the beta position with high stereoselectivity. The stereochemistr y and conformation of the products 2 and 4 in solution have been eluci dated based upon NOE experiments and (n)J(PX) (n = 1-4, X = C, H) data . Large negative (4)J(PH) coupling constants from a predominant n cont ribution were observed from which conformational information could be derived. (3)J(PC) values are positive and follow the expected Karplus model, and values (2)J(PC) show a large stereochemical dependence. The activation energies for the isomerization of the C=C double bond as w ell as for the rotation around the C-N single bond of he enamine linka ge have been calculated. The crystal structures of rbonyl)vinyl]-2,2-d iphenyl-4-(p-tolyl)-1,5-diaza-2 lambda(5)-phosphapenta-1,3-diene (2a) [P2(1)/ c, a = 15.332(6) Angstrom A, b = 17.154(4) Angstrom A, c = 12. 127(3) Angstrom A, beta = 101.40(3)degrees, Z = 4] and bonyl)vinyl]-2, 2-diphenyl-4-cyclohexyl-1,5-diaza-2 lambda(5)-phosphapenta-1,3-diene ( 2d) [P2(1)/c, a = 12.167(7) Angstrom A, b = 21.14(4) Angstrom A, c 12. 845(7) Angstrom A, beta = 108.77(6)degrees, Z = 4] have been elucidate d by single-crystal X-ray diffraction. Calculated conformations by MM and PM3 methods were in good agreement with the experimental observati ons.