Reactivity of organozinc derivatives of phosphinines

The reactions of the 2-organozinc derivatives 1, 2, and 3 of 4,5-dimethylphosphinine with electrophiles of phosphorus, arsenic, tin, copper, silver, and mercury are discussed. The reactions of 2 and 3 with arsenic trichloride furnished the monosubstitution products 4 and 5, respectively, which were not isolable in pure form. Reactions of 2 and 3 with phosphorus electrophiles were partially successful, but the monosubstitution products 8 and 11, respectively, were not formed selectively; among the byproducts were 7, 9, and 10. Transmetalation reactions with tin electrophiles gave 13 (37%) and 16 (7%), which were isolated in pure form. Transmetalation of 2 with a copper salt furnished copper derivative 17, which was trapped below -80 degrees C with a Michael acceptor and chlorotrimethylsilane to give the 1,4-addition product 19. This compound was obtained in nearly pure form in a yield of 20% relative to the 2-iodophosphinine 10. Transmetalation of 3 with a copper salt furnished the copper derivative 20, which decomposed within 6 h at room temperature. This compound was also prepared via direct insertion of reactive Cu(0) into 12. Transmetalations with silver salts afforded the organosilver derivatives 21-21 ''. These silver species turned out to be rather unstable at room temperature. Transmetalation reactions with mercury salts were successful with 1, 2, and 3. The organomercury derivative 22 obtained via 1 and 2, respectively, decomposed at room temperature, but was characterized by H-1, C-13, and P-31 NMR spectroscopies. The relatively stable organomercury derivative 23, obtained from 3, was isolated in a yield of 50% relative to 10.