Total Syntheses of C‐3a‐Prenylated Hexahydropyrrolo[2,3‐<i>b</i>] Indoline Alkaloids

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.