碳水化合物衍生的手性膦及其配位的cis-和trans-铂(Ⅱ)化合物的合成

Synthesis of a New Carbohydrate-Derived Chiral Phosphine and Its Coordinating cis-and trans-Pt(Ⅱ) Complexes

通过硼烷对三级有机膦的配位保护,避开了甲基化试剂对膦官能团的季膦化作用,以甘露糖环氧物为原料经4步反应以55%总产率制得甲基2-O-甲基-3-脱氧-3-二苯膦基-4,6-O-苯次甲基-α-D-吡喃阿糖苷(5).制得的含碳水化合物单元的新手性膦5分别与cis-[Pt(DMSO)2Cl2]和trans-[Pt(NCMe)2Cl2]反应制得相应的cis-和trans-[Pt(5)2Cl2](6和7).实验中发现:(1)在烷氧根负离子存在时,硼烷优先与三级膦配位形成膦硼烷加合物;(2)室温下四氢呋喃中糖环上二级醇形成的烷氧根锂盐不能有效地与碘甲烷发生反应,而相应的钠盐顺利地形成目标产物;(3)有机碱是有效的脱硼烷试剂,而乙醇则有更好的反应结果,后处理简便且可几乎定量地得到产物;(4)偶合常数1JPt-P可作为指认这类含碳水化合物单元的手性膦配位的Pt(II)络合物几何构型的可靠参数.

Via four steps of nucleophilic ring-opening of a-D-manno-epoxide with Ph2P anion, adduction of boranes to phospnine, methylation of hydroxyl, and deprotection of the phosphine-boranes adduct, afforded the desired methyl 3-deoxy-3-diphenylphosphino-2-O-methyl-4,6-O-phenylmethenyl-a-D-pyranoaltroside （5） in 55% of yield. It was found that： （1） the adduct of boranes to the carbohydrate-based phosphine was formed smoothly in the presence of alkyloxide, （2） the alkoxide derived from the secondary alcohol of pyranoside was methylized with MeI as in its sodium salt other than in lithium salt in THF at room temperature, and （3） the deprotection of boranes from the carbohydrate-based phosphine adduct went smoothly by several of organic bases, but more efficiently by ethanol. The corresponding cis- and trans-[Pt（5）2C12] formed by the reaction of the carbohydrate-based phosphine 5 with cis- and trans-[Pt（NCMe）2C12], respectively. The coupling constant 1J Pt-P was reliable to assign the configuration of the geometrical stereoisomers of Pt（II） complexes with the carbohydrate-based phosphine.