SYNTHESIS OF PH(2)PCH(2)C(O)H - A REINVESTIGATION - MOLECULAR-STRUCTURE OF [PH(2)PCH(OH)CH(2)PPH(2)CH(OH)CH2]CL-2 - COMPARED COORDINATIVE PROPERTIES OF PH(2)PCH(2)C(O)H AND PH(2)PCH(2)C(O)NME(2)

The synthesis of Ph(2)PCH(2)C(O)H has been reinvestigated. This highly reactive phosphine aldehyde may be obtained in three steps in 64% ove rall yield according to the following route: (i) preparation of Ph(2)P CH(2)CH(OEt)(2) (1) by reaction of Ph(2)PLi with BrCH2CH(OEt)(2); (ii) treatment of 2 with HCl resulting in formation of the di-phosphonium salt [Ph(2)PCH(OH)CH(2)PPh(2)CH(OH)CH2]Cl-2 (2); and (iii) neutralizat ion of a solution of 2 with NaOH affording 3. The molecular structure of one diastereomer of dication 2 has been determined crystallographic ally. Phosphine 3 behaves as a monodentate ligand in [Pd(o-C(6)H(4)CH( 2)NMe(2))Cl{Ph(2)PCH(2)C(O)H}] (5). Reaction of 5 with LiN(SiMe(3))(2) afforded the enolate complex [Pd(o-C(6)H(4)CH(2)NMe(2)) {Ph(2)PCH=C(O )H}] 6 in 92% yield. The related complex [Pd(o-C(6)H(4)CH(2)NMe(2)) {P h(2)PCH=C(O)NMe(2)}] 8 was also prepared for comparison.