Reactions of Bis[Diphenyl‐3‐(4‐Methoxyphenylsydnonyl)]Phosphine Palladium Chloride and Phosphorus Ligands and Crystal Analysis of Its Phosphite Adduct

Abstract

Re ac tions of bis[di phen yl-3-(4-methoxyphenylsydnonyl)]phos phine pal la dium chlo ride and phosphines or phos phites were per formed yield ing cis-dichloropalladium com plexes. Com plexes have been char ac terized by spec tro scopic tech niques (com pounds 5-13) and by X-ray dif frac tion for com pound 5. Bond lengths of P-C(10) and P-C(16) de creased more than that of P-C(s) af ter com plex for ma tion sug gest ing that the phenyl rings were able to con trib ute more elec tron den sity to phos pho rus for bind ing with Pd(II) than the sydnone ring does. The equi lib rium con stants and rate con stants for the re ac tion be tween com plex 4 and phospho rus lig ands de pend not only on the ba sic ity but also on steric size (i.e., cone an gle) of phos pho rus lig ands used.

Palladium catalyzed molecular cascades for the synthesis of ethyl 2-methyl-2-(4-methyl-3-(morpholinomethyl)-2-oxopent-3-en-1-yl)-1-oxo-1,2,3,4,5,6-hexahydro-3aH-indene-3a-carboxylate

“…From these results it comes that the equivalents of base has to be up to 5 but the amounts of the capping agent morpholine must not exceed 1.5 equiv. Having Ph3P a cone angle of 145, [16][17][18][19][20][21] we started trying different phosphines with increasing cone angle values along with n-Bu3N as a base aiming to ameliorate the cascade results (vide infra). The use of phosphine with lower cone angle (Table 1, Entry 4) determined a lowering of the yields in cascade product 5 (14%) but also poor yields in shunt compounds 6 and 7 (7% and 5%, respectively).…”