Δ3-Dihydropyrans and tetrahydropyrans by reduction of pyrylium salts with sodium borohydride in acetic acid
作者:Teodor-Silviu Balaban、Alexandru T Balaban
DOI:10.1016/s0040-4039(00)95365-6
日期:1987.1
major reduction products with triacetoxyborohydride (NaBH4 in AcOH) of 2,4,6-trisubstituted pyrylium salts bearing alkyl substituents in the 2- and/or 6- position are the Δ3-dihydropyrans with 2- and 6- substituents and the all--2,4,6-trisubstituted tetrahydropyrans. Δ3-Dihydropyrans are shown to be formed 2H-pyrans by a 1,4 reduction while tetrahydropyrans result from 4H-pyrans by reduction of both
主要还原产物与三乙酰氧基硼(加入NaBH 4的AcOH)2,4,6-三取代的吡喃鎓盐轴承烷基取代基在2-和/或6-位置是Δ 3 -dihydropyrans与2-和6-取代基和全-2,4,6-三取代的四氢吡喃。Δ 3 -Dihydropyrans被示出为形成由1,4-还原2H吡喃而四氢吡喃通过还原既烯醇-醚双键的从4H-吡喃导致。