Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-4(1H)-pyridinone, and 1,2,3,4-Tetrahydropyridinesvia N-AcylN,O-Hemiacetal Formation
作者:Jean-Paul Roduit、Hugo Wyler
DOI:10.1002/hlca.19850680214
日期:1985.3.27
New procedures are described for the synthesis of α,β-ethylenic and acetylenic aldehydes from 2-butene- and 2-butyne-1,4-diol, respectively (see Scheme 1). These are applied to the preparation of a particular δ-acetylamino-α,β-ethylenic aldehyde ((E)-5) as well as of its acetylenic analogue 15. On heating in the presence of a silyl enol ether, the former undergoes a complete dehydrative cyclization
描述了分别由2-丁烯-和2-丁炔-1,4-二醇合成α,β-烯醛和炔属醛的新方法(参见方案1)。这些适用于制备特定的δ-乙酰氨基-α,β-乙烯醛((E)-5)及其炔类似物15。在甲硅烷基烯醇醚存在下加热时,前者经历完全的脱水环化,得到N-乙酰基-1,2-二氢吡啶19。将HCl添加至醛(E)-5中导致产生4-氯-1,2,3,4-四氢吡啶22,其被水解为相应的醇23在硅胶上。类似地,向δ-乙酰基-氨基-α,β-炔属醛15中加入HCl或HBr会导致先前未知的4-卤代-1,2-二氢吡啶26 ; 这些很容易水解为2,3-二氢-4(1 H)-吡啶酮27。成环过程涉及N-酰基N,O-半缩醛作为中间体,其最终被脱水。