Pentacovalent phosphorus. II. Reactions of dione and lactone dimers of dimethylketene with trivalent phosphorous acid amides

Abstract

Reactions of the dione 1 and lactone 2 dimers of dimethylketene with the phosphoramidites (CH30)2PN(CH3)2 (3), CH3OP[N(CH3)2]2 (4), and CeHsOP[N(CH3)2]2 (5) and with trisdimethylaminophosphine (6) were investigated. Carboxy esters resulted from reactions of 3 and 4 with either dimer while 5 and 6 gave carboxamides. The structures of these products are similar to those formed from dimethylketene dimers on reaction with trialkyl phosphites. Except for reactions of 3, identical products were formed from either 1 or 2 and a given phosphorus derivative. On reaction of 1 and 3, three products are formed in relative proportions dependent on reaction temperature. These reactions are discussed in terms of a postulated mechanism involving nucleophilic attack by phosphorus on carbonyl carbon of 1 or 2, followed either by ring expansion to a cyclic pentacovalent phosphorus intermediate or by ring opening to a phosphonium enolate species. Isomerization of 1 to 2 in the presence of 5 or 6 is also accommodated by the suggested reaction series. Possible kinetic control of carboxamide vs. carboxy ester formation is treated in terms of the structures and reaction patterns predicted for the postulated pentacovalent intermediates. II), All show a weak ir band at about 1665 cm-1 for (4) R.

Structural and electronic influences on phosphite basicity and its application to heterogeneous and homogeneous catalysis

“…g-Chloro-4,6-o,a-dimethyl-l,3,2-dioxaphosphorinane (£) The preparation of this compound can be found in chapter one of this thesis.Dimethylphosphochiorodite(40) This compound was prepared via the procedure of Ramirez and co-workers(146).Dimethyl dimethylphosphoramidite(41) Attempts to prepare this compound via the reaction of 1 equivalent of tris(dimethyl amino)phosphine and two equivalents of methanol in the presence of a catalytic amount of dimethyl ami ne hydrochloride via the method of Bentrude and co-workers(147) were unsuccessful. The compound was successfully prepared via the reaction of and dimethyl amine in a manner similar to a procedure described previously(128).The compound was obtained in 73% yield via distillation (b/^2 = 42-45°, lit.…”