|Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2001: ¥2,300,000 (Direct Cost: ¥2,300,000)
Structurally complex alkaloidal sugar mimics with a nitrogen in the ring have been isolated from plants and microorganisms and inhibit various glycosidases in a reversible and competitive manner. Since such glycosidase inhibitors proved to have the potential to produce antiviral, insect antifeedant, antidiabetic, and anticancer effects as well as immune modulatory properties, they have held considerable interest in the context of the synthesis of nitrogen-containing natural products.
Towards the carbonyl group of imides, on the other hand, two reactions, i.e., an intramolecular Barbier-type reaction of some N-iodoalkyl cyclic imides and a coupling reaction of acyclic imides such as N-acyllactams with carbonyl compounds are known. In this connection we have also recently reported the first pinacolic cross-coupling reaction between phthalimides and carbonyl compounds and its application to the complete stereoselective deoxygenation. However, the lack of studies concerning the reactivity of samarium (II) compounds towards simple amides is surprising except in some special cases. This should be attributed to their low reactivity.
Herein we described the first nitrogen-carbon (hetero) coupling reaction between lactams and aldehydes mediated by SmI_2 to provide N-α-hydroxyalkylated lactams and its application to the short synthesis of biologically active indolizidine alkaloids, (-)-δ-coniceine, (+)-5-epiindolizidine 167B and (+)-lentiginosine in addition to the formal synthesis of an isoindolobenzazepine alkaloid, chilenine.