Reductive Cyclizationによる4-Oxa-9-aza-9-methyl-6,7-benzobicyclo[3.3.1]nonane合成ならびに本反応によるPiperidone誘導体の還元的閉環の試み : 複素環式化合物の合成研究 第227報

抄録

Reduction of 3-(methoxycarbonylmethyl)-2-methyl-3, 4-dihydroisocarbostyril (VIII) with lithium aluminum hydride gave the anticipated cyclization product, 4-oxa-9-aza-9-methyl-6, 7-benzobicyclo [3. 3. 1] nonane (X), with by-product formation of 2-methyl-1, 2, 3, 4-tetrahydroisoquinolin-3-ethanol (XII) and 3-(2-hydroxyethyl)-2-methyl-3, 4-dihydroisocarbostyril (IX). Reduction of IX with lithium aluminum hydride also gave the cyclized reduction products, X and XII, while the sme reduction of X gave the ringcleaved product, XII. It is interesting that 2H-tetrahydro-1, 3-oxazine ring is formed by the reduction of VIII or IX. Application of this reaction to nine kinds of new piperidone compounds (XVI to XXIV) failed to afford the anticipated cyclized products (XXXII to XXXVI) and only the ringcleaved products (XXVII to XXXI) were obtained.