A Diastereodivergent Synthetic Strategy for the Syntheses of Communesin F and Perophoramidine

Abstract

An efficient, unified, and stereodivergent approach toward communesin F and perophoramidine was examined. The C(3) all-carbon quaternary center of an oxindole was smoothly constructed by base-promoted indolone-malonate alkylation chemistry. The complementary relative stereochemistry of the crucial vicinal quaternary centers found in communesin F and perophoramidine was selectively installed by substrate-controlled decarboxylative allylic alkylations.

Stereochemical evaluation of bis(phosphine) copper catalysts for the asymmetric alkylation of 3-bromooxindoles with α-arylated malonate esters

“…Bromooxindole 5 was easily prepared from indole in four steps by a known sequence, 5 which was then added to o -nitrophenyl dimethylmalonate 12 and cesium carbonate in THF solvent to afford a racemic product 13 in good yield. (Scheme 3).…”

“…5,6 We envisioned that the stereochemistry at the vicinal quaternary centers on communesin F and perophoramidine could be installed utilizing the conditions described in Scheme 1b. However, attempts to produce diesters 8 and 9 via copper(II) bisoxazoline catalyzed enantioselective alkylation of 3-bromooxindoles 4 and 5 with α-arylated malonate esters 6 and 7 were unsuccessful (Scheme 2).…”

Advances in Stereoconvergent Catalysis from 2005 to 2015: Transition-Metal-Mediated Stereoablative Reactions, Dynamic Kinetic Resolutions, and Dynamic Kinetic Asymmetric Transformations

“…Chirality is transferred from the ligand to generate a variety of enantioenriched 3,3-disubstituted oxindole motifs ( 68 ). The Stoltz group has utilized this strategy for the syntheses of communesin F 82 and perophoramidine. 83 …”

A new method for the cleavage of nitrobenzyl amides and ethers

“…5 o -Nitrobenzyl groups have been used as photocleavable protecting groups for amides and heterocycles such as indoles, benzimidazole, and 6-chlorouracil as well as the more common hydroxyl group. 6,7 In addition, a method for removing p -nitrobenzyl groups on hydroxyl groups in two steps by reduction to a p -aminobenzyl group followed by electrochemical oxidation was disclosed by the Kusumoto group.…”

“…The o -nitrobenzyl group on a highly functionalized communesin F intermediate 5 was smoothly cleaved under our standard conditions in good yield (entry 1). 5 p -Nitrobenzyl groups on amide 7 and lactam 9 were also cleaved in moderate yields (entries 2 and 3). The p -nitrobenzyl group on urea 11 was also successfully cleaved and methyl 4-nitrobenzoate was isolated as a by-product (entry 4).…”