The Synthesis And Reduction Of Pd（OAc）₂ Catalyzed α-substituted Vinyl Phosphate And Vinyl Sulfone

Alkenyl phosphonic acid ester and alkenyl sulfone is an important intermediates in the organic synthesis industry. This paper briefly introduced the methods for preparing of alkenyl phosphate and alkenyl sulfone, and put forward an efficient preparation of α-vinyl phosphate and α-vinyl sulfone by Suzuki-Miyaura cross-coupling reaction.(1) In the first part, we developped a new method for α-substituted vinyl phosphate: the palladium catalyst cross-coupling reaction ofα-vinylphosphonates nonaflate and aryl boric acid with different substituents of nucleophilic couplet. The reaction conditions were investigated by using 2-methyl benzene boric acid as the substrate. The optimal reaction conditions were:arylboronic acid(1.5 equiv), the catalyst being Pd(OAc)2(5 mol %), ligands being SPhos or XPhos(10 mol %), Cs2CO3(2.5 equiv) being the base and toluene being the solvent at room temperature, after 5-8 h the yield being over80 %. The scope of arylboronic acid is investigated. With the aromatic groups with electron withdrawing groups or electronic groups, the coupling reaction yields are from pretty good to excellent. When the coupling structure with three or four substituted alkenyl phosphonates, the reaction can reach good yields.(2) In the second part, we use the Suzuki cross-coupling reaction strategy for the preparation of α-substituted vinyl sulfone. By using α-substituted bromine vinyl sulfone and 3,4- methoxybenzeneboronic acid as the substrates,the reaction conditions were investigated. The optimum reaction conditions were:arylboronic acid(1.5 equiv), Pd(OAc)2(5 mol %), SPhos(10 mol %), Cs2CO3(2.5 equiv) being the base and the toluene being the solvent at 50 ℃, after 15 h the productivity are from pretty good to excellent. Change the different boronic acid, there still 70 % to 99 % yields were achieved. This part was also investigated the complex structures of the estrone derivative with 88 % yield.Thus, the method has a good compatibility with complex organic compounds.(3) NBSH is widely used in a variety of olefin reductions, because of its selective reduction, it is used in a variety of selective reduction reactions. This paper selects the reducing agent to have the α-substituted vinylphosphate andα-vinylsulfone reducted. The NBSH(2.0 equiv), the base being K3PO4 or Na2CO3(1.0 equiv), after 5 h in room temperature, the reaction would ended.Some steric larger substrates such as α-2-methylvinylphosphate,α-2-chlorvinylphosphonate and α-1-naphthylvinylphosphonate need to put NBSH four times to get a good yield of reduction.