Total Synthesis of naturally occurring lactones and Semiplenamides C and E and Investigation on Novel Diterpenoids of Jatropha Multifida

Abstract

The present study is focussed on the stereoselective total synthesis of some naturally occurring lactones, semiplenamides and isolation of bioactive natural products. newline6-Substituted-5,6-dihydro-2H-pyran-2-one is an important structural subunit in many biologically promising natural products. newline(6 S)-5,6-Dihydro-6-[(2 R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one and dodoneine are amongst them that attracted our focus for newlinesynthesis due to their interesting biological activities and structural similarities. The pyranone unit of both molecules was brought newlinethrough a common intermediate with varying asymmetric centres. These lactone intermediates, ( S) - and ( R)-2-(6-oxo-3, 6-dihydro-2H-pyran-2-yl) acetaldehydes have further been accomplished from 1,3- newlinepropanediol employing Maruoka asymmetric allylation and ring closing metathesis reaction. These intermediates were converted into desired natural products (6 S)-5,6-Dihydro-6-[(2 R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one and dodoneine through Grignard newlinereaction.