Synthesis and sequential diastereoselective incorporation of hydroxyl groups into hexahydrofuro[3,2-f]indolizin-7(2H)-one to give mono-, di- and tetra-hydroxyfuroindolizidines

Diastereoselective Synthesis of Tetrahydrofurano[2,3-g]indolizidine and 8-Aminoindolizidines from L-Asparagine

8-Aminoindolizidines were synthesized from L-asparagine as the chiral starting material. The key dibenzylamino succinimide intermediate was synthesized in two steps. Three homologs of chiral hydroxylactams tethered with hydroxyalkene were synthesized from the succinimide via a sequence involving N-alkylation, cross olefin metathesis and hydride reduction. The dibenzylamino group gave the stereocontrol of the key N-acyliminium ion cyclization of these hydroxylactams. 5-Substituted-aminoindolizidines were synthesized with high diastereoselectivity at C6. A tandem cyclization of N-(6-hydroxyhex-3-en-1-yl)-g-hydroxylactam resulted in formation of tetrahydrofurano[2,3-g]indolizidine system.

Smart and concise entry to chiral spiro[cyclopentane-indolizidine]-tetraol diastereomers as a new aza-spirocyclic framework

Synthesis of chiral oxacarba-spiroindolizidine tetraols was achieved by alkene cis-dihydroxylation, diol protection, and lactam carbonyl reduction followed ultimately by acetonide deprotection.