Zirconium-promoted ring opening. Scope and limitations

Hydrozirconation by means of [Cp(2)ZrHCl](n) (2) of phospholene PhPCH(2)CH=CHCH2 (1) leads to the beta-zirconated phospholane 3 which reacts with phosphenium salts R(2)P(+)OSO(2)CF(3)(-) (4, R = N(i)Pr2; 5, R = NCy(2)) to give unsaturated acyclic, 1,1-diphphosphines 6 Or 7. Compound 3 also reacts with other electrophiles like [CH2=NMe(2)]Cl, (t)BuCOCl, or HOSO2CF3 loading to unsaturated phosphines PhP(R)(CH2)(2)CH=CH2, 8 (R = CH(2)NMe(2)), 9 (R = C(O)(t)Bu), or 10 (R = H), respectively. Hydrozirconation of 2,5-dihydrofuran (12) or 2,3-dihydrofuran (13) affords the acyclic zirconated species Cp(2)Zr(Cl)O(CH2)(2)CH=CH2 (15), which. reacts with 4, PhPCl, [CH2=NMe(2)]Cl, PhCOCl, or HOSO2CF3 to give, via exchange reactions, the corresponding substituted olefines 16-20. Treatment of 12 or 13 with 2 equiv of 2 leads to dizirconated compound Cp(2)Zr(Cl)O(CH2)(4)(Cl)Cp(2) (21) which reacts with Ph(2)PCl (2 equiv) to give the phosphino-phosphinite Ph(2)PO(CH2)(4)PPh(2) (22) isolated as its disfulide 23, 2-Methyl-4,5-dihydorfuran (24) treated first with 2 equiv of 2 and then with 2 equiv of Ph(2)PCl affords the phosphino-phosphinite Ph(2)PO(CH2)(5)PPh(2) (26). Hydrozirconation of 2,5-dimethoxy-2,5-dihydorufan (28) with 2 equiv of 2 gives rise to Cp(2)Zr(OMe)Cl (31) and Cp(2)Zr(Cl)O(CH2)(2)CH=CHOMe (33), which react further with Ph(2)PCl (2 equiv) leading to phosphinites Ph(2)POMe (34) and Ph(2)PO(CH2)(2)CH=CHOMe (35). Addition of 2 to 1-benzyl-3-pyrroline (36) allows the formation of the beta-zirconated nirogen five-membered ring PhCH(2)N(CH2)(2)CH(ZrCp(2)Cl)CH2 (37). 37 reacts with Ph(2)PCl giving rise to the acyclic aminophosphine Ph(2)PN(CH(2)Ph)(CH2)(2)CH=CH2 (38) and to a substitute pyrroline 39. Derivative 37 also reacts with 4 to give the saturated nitrogen heterocycle 42, while it reacts with PhCOCl or HOSO2CF3 to afford the corresponding linear species PhC(O)N(CH(2)Ph)(CH2)(2)CH=CH2 (44) or the amine HN(CH(2)Ph)(CH2)(2)CH=CH2 (45). Hydrozirconation of 38 followed by addition of Ph(2)PCl and then addition of S-8 gives the aminophosphine-phosphine disulfide Ph(2)P(S)N(CH(2)Ph)(CH2)P(S)Ph(2) (46). Hydrozirconation of oxygen six-membered rings such as 3,4-dihydro-2H-pyran (53) and 2-methoxy-3,4-dihydro-2H-pyran (55) is discussed as well as the hydrozirconation of a seven-membered ring, cis-dihydro-1,3-dioxepin (62). The behavior of 3-sila- (47) or 3-boracyclopentene (48) is also presented.