Studies Aimed at the Total Synthesis of Azadirachtin as an Insect Antifeedant

Abstract

Efficient construction of the respective right and left segments of azadirachtin is described. Furthermore, studies on the connection between both the segments are also mentioned; the Ireland‐Claisen rearrangement of Li‐enolate of the modelled ester with dichlorodimethylsilane in toluene afforded the desired limonoid framework stereoselectively in good yield.

Keywords: :

• Azadirachtin
• Total synthesis
• Intramolecular Diels‐Alder reaction
• Ireland‐Claisen rearrangement

Notes

^aFor comprehensive reviews on 1, see: Govindachari and Gopalakrishnan (1998), Mordue (Luntz) and Blackwell (1993).

^bVery recently, the sought‐after free carboxylic acid corresponding to the methoxycarbonyl group of compound 15 has been prepared in high yield by the modified procedure in our laboratory. Fukuzaki, T. part of the dissertation, Hokkaido University, 2003.

^cPreparation of the optically pure decalin (35) is included in Supporting Information of Fukuzaki et al. (2002).

^dVery recently, Ley showed the utility of Claisen rearrangement of allyl vinyl ether in the formation between C‐8 and C‐14 in 1. See: Durand‐Reville et al. (2002), Ley et al. (1999).