Asymmetric Total Syntheses of Communesin F and a Putative Member of the Communesin Family

Abstract

Here we report asymmetric total syntheses of communesin F and a putative member of the communesin family of bis-aminal alkaloid natural products. The successful strategy featured the invention of an asymmetric organocatalytic reaction to unify two oxindole subunits, a Ti(O Pr) -mediated dehydrative skeletal rearrangement, and a late-stage Pd(OAc) -catalyzed directed CH-alkenylation reaction. Collectively, the synthetic technologies disclosed herein enabled the preparation of a late-stage polycyclic intermediate catered for the synthesis of both naturally occurring and designed communesins. More importantly, speculated and yet to be discovered member(s) of the communesin family can now be accessed to facilitate a better understanding of the communesin biosynthetic network.

Asymmetric Catalytic Concise Synthesis of Hetero-3,3′-Bisoxindoles for the Construction of Bispyrroloindoline Alkaloids

“…The hetero-coupling of two oxindole units is based on the addition of 3-substituted N-Boc oxindoles 1 to o-azaxylylene, generated from 3-substituted 3halooxindoles 2, with the assistance of a base. [27][28][29][30][31][32][33][34][35] Racemic products were obtained in moderate yield with poor diastereoselectivity in the presence of either an organic or inorganic base. As described in Scheme 2, N-Boc-protected oxindole 1a and 3-bromo-3methyloxindole 2a were selected as the model substrates to show the efficiency of this route.…”

Diastereoselective Syntheses of Spiro[indoline-3,4′-pyridin]-2-yl Carbamates via AgOTf/Ph3P-Catalyzed Tandem Cyclizations of Tryptamine-Ynesulfonamides

“…Spiro­[indoline-3,4′-piperidine] is a significant structural scaffold in a number of polycyclic indole alkaloids such as (−)-communesins A-H, (+)-perphoramidine, and some other bioactive compounds like ibutamoren, a potent nonpeptide growth hormone secretagogue receptor (GHSR) agonist (Figure ). The significance and prevalence of this structural scaffold have motivated the development of many elegant synthetic strategies to the family of communesins and pherophoramidine . For example, in 2006, Rainier and co-workers developed an intramolecular coupling strategy to give a spiro­[indoline-3,4′-piperidine] scaffold (Scheme a) .…”

Palladium‐Catalyzed meta‐Selective C‐H Alkenylation and Acetoxylation of Arylacetic Acid Using a Pyrimidine Template

“…The direct C‐H bond functionalization has been recognized as a promising method to synthesize useful organic compounds from inert molecules In the past decades, more attentions have been paid to the transition‐metal catalyzed C‐H bond functionalization to construct various C‐C or C‐X (N, O, S) bonds . In contrast to the widely developed directing‐group‐assisted ortho ‐C‐H functionalization of arenes, the direct meta ‐C‐H functionalization has proved to be more challenging due to its difficulty in forming the macrocyclic metallacycle intermediate with high energy transition state .…”