Total Synthesis of Indotertine A and Drimentines A, F, and G

Abstract

Oh my darling, Drimentine: The first total synthesis of the pyrroloindoline alkaloids drimentines A, F, and G, and their congener, indotertine A, is reported. An intermolecular radical conjugate addition was key in the synthesis of the drimentine alkaloids, and a biologically inspired iminium–olefin cyclization converted drimentine F into indotertine A.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

“…Alkaloids 647-649 were accessed from 653, and 649 was transformed into 650 (Scheme 132). 208 The single-step asymmetric introduction of an isoprenyl group on C3a of a pyrroloindoline core was developed based on the silver-promoted Friedel-Cras reaction. Treating bromopyrroloindole 658 and prenyl tributylstannane 659 in the presence of AgBF 4 produced prenylated intermediate 660, which was then transformed into (À)-ardeemin (655), (À)-formylardeemin (656), and (À)-acetylardeemin (657) (Scheme 133).…”

Lewis Acid Catalyzed Displacement of Trichloroacetimidates in the Synthesis of Functionalized Pyrroloindolines

“…15 In order to explore this chemistry a C3a-hydroxy pyrroloindoline was required. While a number of methods have been reported for the synthesis of C3a-hydroxy pyrroloindolines, 8e,8f,12a,16 the oxidation reported by Takayama and co-workers 17 which employs m -CPBA and TFA seemed to provide the most direct access. When protected tryptamine 6 was exposed to these conditions a 59% yield of pyrroloindoline 7 was obtained.…”

Synthesis of 2,5-Diaryl-1,5-dienes from Allylic Bromides Using Visible-Light Photoredox Catalysis

“…1,2 In the area of free radical reactions, visible-light photocatalysis is allowing a variety of such processes to be accomplished without the use of stoichiometric adjuvants such as tin reagents. A variety of precursors such as halides, 1d,1f,3 selenosulfonates, 4 sulfonium 5 and sulfonyl 6 derivatives, diazonium salts, 7 carboxylic acids, 8 ( N -acyloxy)phthalimides, 9 N -phthalimidoyl oxalates, 10 enamines, 11 and other α-amino substituted compounds 12 can be used to generate carbon radicals under these conditions.…”