Chemistry of tetrahydro-1,3-oxazin-2-one: New method for the synthesis of indoloquinolizidine derivatives

Article abstract of DOI:10.1248/cpb.39.3157

The aldol condensation of the N-Boc-tetrahydro-β-carboline-1-acetate (4) with acrolein in the presence of lithium diisopropylamide (LDA) gave an allyl alcohol (6), which was then treated with methanesulfonyl chloride and triethylamine to give a mixture of the mesylate (8) (55%) and the indolopyrido-3,5-oxazin-4-one (10) (14%). When 8 was treated with 1,8-diazabicyclo[5.4.0.]-7-undecene (DBU) in dimethylsulfoxide (DMSO) at room temperature, the azetopyridoindoles (12 and 13) were obtained unexpectedly. Alternative preparation of the indolopyrido-3,5-oxazin-4-ones (15 and 16), which are stereoisomers of 10, from 6 followed by heating with DBU in DMSO gave several indoloquinolizidines (18, 19 and 20), which are key intermediates for the synthesis of the indole alkaloids vindolosine and vindoline.

Full text of DOI:10.1248/cpb.39.3157

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