通过对水的用量、催化剂、醛与溴丙烯的比例、反应温度等因素对反应的影响的探索，发现了水相中Barbier-Prins 环化串连的一锅法合成2，4，6-三取代全顺式四氢吡喃的新反应。反应达到了原子利用率高，对环境友好，可在水相中进行反应的目的。

The reaction of [MnRe(CO)6(

Complexes [Mn2(CO)6(µ-S2CPR3)] (R=Cy(1a), Pri (1b)) are reduced with Na[Hg] in THF to afford the anions [Mn2(CO)6(µ-S2CPR3)]2-(2a,b), which give neutral unstable [Mn2(CO)6-(µ-SH){µ-SC(H)PR3}(NH3)] (3a,b) upon protonation with excess NH4PF6. The NH3 ligand of 3a,b is readily replaced by PEt3 to obtain [Mn2(CO)6(µ-SH){µ-SC(H)PR3}(PEt3)] (5a,b) as stable crystalline solids, which have been isolated and characterized. The same reduction/protonation sequence when applied to the dirhenium analogue [Re2(CO)6(µ-S2CPCy3)] (1c) affords stable crystalline [Re2(CO)6(-SH){µ-SC(H)PCy3}(NH3)] (6). An X-ray determination revealed that 6 contains one bridging SH-and the novel ligand Cy3PC(H)S-which is bonded as µ2-η1(S);η2(C,S'), donating 5e to the metals. Both bridging ligands are produced from the cleavage of one C-S bond of the starting S2CPR3 during the reduction/protonation process, which can be regarded globally as hydrogenolysis of the C-S bond. Additionally, the Re-Re bond is also cleaved during the process. As their dimanganese analogues, 6 undergo easy substitution of NH3 by PEt3 to give [Re2(CO)6(µ-SH){µ-SC(H)PCy3}(PEt3)] (7). Comparison of the spectroscopic data indicate that both series of compounds are isostructural, with the only difference being the higher stability of the dirhenium complexes when compared to those of dimanganese.

The reaction of [M(CO)3(S2CPR3)Br] (M=Mn, Re) with Co2(CO)8 produces the heterobi-nuclear complexes [MCo(CO)5(μ-S2CPR3)] (2). An X-ray determination of the derivative with M=Mn, and R=Cy [2a, triclinic, space group P1, a=11.074(3) A, b=11.156(3) A, c=11.769(3) A, a=74.64(1)°,β=85.36(1)°, γ=83.44(2)°, Z=2, R=0.042, Rw=0.043] showed the formation of a Mn-Co bond, and the presence of the S2CPR3 ligand coordinated as a η2(S,S') chelate to Mn and as a η3(S,C,S') pseudoallyl to Co. The structure of 2a, and the spectroscopic data of all derivatives 2a-d indicate that the central carbon of the S2CPR3 ligand shows a definite preference for attachment to cobalt rather than to manganese or rhenium and that the reaction produces specifically the compounds with the carbon bonded to the cobalt atom. Although the reactions could be considered as involving the disproportionation of Co2(CO)8 into Co-Ⅰ and CoⅡ, it is noticeable that the direct reaction of the starting [M(CO)3(S2CPRs)Br] with Co(CO)4-gives complexes 2 only for M=Re, but not for M=Mn. The method can be extended to prepare complexes containing Mo-Co and W-Co bonds. Thus, Co2(CO)8 reacts with [M(η3-C3H5)(CO)2(S2-CPR3)Br] (3; M=Mo, W) to produce [MCo(η3-C3H5)(CO)4(μ-S2CPR3)] (4a-d) in moderate yields. An X-ray structure determination of the derivative with M=Mo, R=Cy [4a.CH2CI2, triclinic, space group P1, a=10.301(1) A, b=11.347(7) A, c=15.723(2) A, a=90.08(2)°, β=102.46(4)°, γ,=112.84(1)°, Z=2, R=0.062, Rw=0.070] established the existence of a direct Mo-Co bond, and the presence of the S2CPCy3 ligand bonded as η2(S,S') chelate to Mo and as a η3(S,C,S') pseudoallyl to Co, in the same fashion observed for the structure of the Mn-Co derivative 2a. Again there is a selective formation of a C-Co bond, which indicates a definite preference of the central carbon to bind cobalt rather than molybdenum. In this case, the formal oxidation states are MoI and Co0 and the preference observed is consistent with our previous observations, which can be rationalized assuming that the central carbon of S2CPR3 prefers to bind the metal atom with the lower oxidation state. A common feature ofthe structures of 2a and 4a is the occurrence of a Co(CO)2 fragment which is bonded to a MSCS' ring which donates formally 5 e. In this sense, the molecules of 2a and 4a are isoelectronic to CpCo(CO)2. Some geometric parameters of the structures of 2a and 4a compare well with those in CpCo-(CO)2, suggesting that there is a close analogy between the two types of molecules.

The anions [MnM(CO)