Total Syntheses of C-3a-Prenylated Hexahydropyrrolo[2,3-b] Indoline Alkaloids
Arindam Maity1, Mrinal Kanti Das2, Pranay Shyamal3
1Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal, Madhya Pradesh, 462 066, India.
Abstract:
Catalytic asymmetric total syntheses of naturally occurring C-3a prenylated hexahydropyrrolo-[2,3-b]indoline alkaloids, such as (-)-debromoflustramines B (1b) and E (1a), as well as (-)-pseudophrynaminol (2a), (-)-pseudophrynamines 270 (2c) and 272A (2b) have been achieved via a thiourea catalyzed aldol reaction of N-boc protected 2-oxindole (13) with paraformaldehyde as C1 unit (upto 90% ee). In this approach, (-)-debromoflustramine E (1a) was utilized as an advanced intermediate for efficient total syntheses of pseudophrynamine alkaloids such as 2a-c via a site-selective allylic oxidation.
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