Desymmetrization of meso-Dicarbonatecyclohexene with β-Hydrazino Carboxylic Esters via a Pd-Catalyzed Allylic Substitution Cascade

Abstract

The desymmetrization of meso-dicarbonatecyclohexene with β-hydrazino carboxylic esters has been achieved via a RuPHOX/Pd-catalyzed allylic substitution cascade for the construction of chiral hexahydrocinnoline derivatives with high performance. Mechanistic studies reveal that the reaction exploits a pathway different from that of our previous work and that the first nitrogen nucleophilic process is the rate-determining step. The protocol could be conducted on a gram scale without any loss of catalytic behavior, and the corresponding chiral hexahydrocinnolines can undergo diverse transformations.

Pd-Catalyzed Asymmetric Allylic Substitution Cascade of Substituted 4-Hydroxy-2H-pyrones with meso-Allyl Dicarbonates

“…Our group has had a long-standing interest in transition-metal-catalyzed asymmetric allylic substitutions . Recently, we have directed more attention to the enantioselective desymmetrization of meso -allyl substrates and established a practical and easily accessible RuPHOX/Pd catalytic system, which has shown excellent catalytic performance in asymmetric allylic substitution cascades for the formation of various chiral heterocycles . To explore the synthetic pathway for chiral tetrahydro-1 H -pyrano­[4,3- b ]­benzofuran-1-ones, we herein reported the Pd-catalyzed asymmetric allylic substitution cascade of 4-hydroxy-2-pyrones with meso -allyl dicarbonates, providing the fused-ring products in high yields and excellent enantioselectivities (Scheme c).…”

Pd-Catalyzed Formal [3 + 3] Heteroannulation of Allylic gem-Diacetates: Synthesis of Chromene-Based Natural Products and Exploration of Photochromic Properties

“…To summarize, we have established an unprecedented Pd­(II)-catalyzed formal [3 + 3] heterocyclization of readily available 2-naphthols and easily accessible allylic gem -diacetates to synthesize a diverse range of chromenes, benzo­[ f ]­chromenes, and pyrano­[3,2- a ]­carbazoles . A noteworthy feature of the reaction is that it does not require additives, bases, oxidants, or inert atmosphere, unlike typical Pd-mediated transformations.…”

Asymmetric cascades of the π-allyl complex: a journey from transition-metal catalysis to metallaphotocatalysis

“…Furthermore, they also studied a similar Tsuji-Trost cascade with the same cyclic allyl dicarbonates 2a and oximes of b-keto esters 6a for the synthesis of hexahydrocinnolines 6b in an enantioselective manner under similar conditions (Scheme 6). 25 In general, both aliphatic and aromatic imines participated in the cascade, eventfully leading to the desired hexahydrocinnolines in good yield and excellent enantioselectivity.…”