The Influence of Heteroatom-substituted Methyl Groups and of Vinyl Groups (CR<sub>2</sub>=CR—) Attached to C-2 of 1,3-Dioxolanes on the Ease and Direction of Hydrogenolysis of the 1,3-Dioxolanes by AlH<sub>2</sub>Cl, AlH<sub>3</sub>, or LiAlH<sub>4</sub>
作者:H. A. Davis、R. K. Brown
DOI:10.1139/v71-422
日期:1971.8.1
AlH2Cl or AlH3 in diethyl ether at room temperature reduces 2-vinyl- or 2-[alkyl (or aryl) substituted vinyl]-1,3-dioxolanes to only the β,γ-unsaturated alkyl β-hydroxyethyl ether, the product expected from hydride ion addition to C-2 of the 1,3-dioxolane. The ease of hydrogenolysis increases with increasing alkyl (or aryl) substitution on the 2-vinyl group.LiAlH4 in diethyl ether at room temperature, or
2-甲基-1,3-二氧戊环的甲基上的杂原子取代基阻碍了 2-取代的 1,3-二氧戊环的醚溶液的 AlH2Cl 的氢解速率。杂原子在降低氢解容易度方面的有效性是 H < S < O < Br < NR2。这种延迟被认为是由于杂原子的电负性和/或一些 AlH2Cl 与杂原子的配位引起的过渡态不稳定导致中间氧碳离子。AlH2Cl 或 AlH3 在室温下乙醚中将 2-乙烯基-或 2-[烷基(或芳基)取代的乙烯基]-1,3-二氧戊环还原为仅 β,γ-不饱和烷基 β-羟乙基醚,预期产物是氢阴离子加成到 C-2 1,3-二氧戊环。