Synthesis of the Benzo- fused Indolizidine Alkaloid Mimics

• Daniel L. Comins and
• Kazuhiro Higuchi

Beilstein J. Org. Chem. 2007, 3, No. 42, doi:10.1186/1860-5397-3-42

• indolizidine alkaloid mimics has been developed. The indolizidine derivatives 8 were prepared via heteroaryl Grignard addition to N-acylpyridinium salts followed by an intramolecular Heck cyclization. Further substitution reactions were developed to demonstrate that heterocycles 8 are good scaffolds for

• from N-TIPS-3-bromopyrrole [18] and N-TIPS-3-bromoindole (entries 8,9). Next, the intramolecular reductive Heck cyclization with N-acyl-2,3-dihydropyridones 1a-i was investigated (Table 2). A short synthesis of indolizidine alkaloids of type 8 by using Heck or anionic cyclization methods was developed

• derivatives containing functionality in the benzene ring was examined. The chloro-substituted compound 1j was prepared from 6 and 4-chloro-2-iodobenzoylchloride (7b). [20] The reductive Heck cyclization of 1j proceeded without difficulty to provide compound 8j in 82% yield (Scheme 1). Next, the nitro