Enantioselective syntheses of the assigned structures of the helibisabonols A and B

Highly Enantioselective Iridium‐Catalyzed Hydrogenation of α,β‐Unsaturated Esters

“…[33] Through the iridium-catalyzed asymmetric hydrogenation of substrate 30 and subsequent conversion of the ester to an acid, we synthesized 32 in 98 % ee and with 95 % yield of the isolated product (Scheme 2). Shishido et al have used (R)-3-(2,5-dimethoxy-4-methylphenyl) butanoic acid (36) in an enantioselective total synthesis of the strongly allelopathic (À)-Heliannuol A. [34] They started from the lipase-mediated transesterification of a prochiral diol to create a chiral monoacetate (78 % ee), which was elaborated in five steps to give 36.…”

Use of chiral auxiliaries in the asymmetric synthesis of biologically active compounds: A review

“…These important chemical messengers regulate many physiological activities, such as blood circulation, blood pressure, growth, inflammation, sleep, digestion, and reproduction . The presence of these substances was first detected in human semen, which is produced in the prostate, hence the name prostaglandins . PGF 2 α is a potent in vitro inhibitor of adipocyte differentiation and has recently been implicated in adipogenesis regulation in vivo.…”

“…A recently reported total synthesis of helibisabonol A had as a key step a diastereoselective alkylation reaction of the Michael acceptor 189 with magnesium dimethylcuprate, providing adduct 190 with a single stereocenter controlled by the Evans' chiral inducer. A few additional steps from 190 provided helibisabonol A in an overall yield of 33% (Scheme ) …”

Stereocontrolled Total Synthesis of Natural Products with Characteristic Molecular Structures and Biological Activities

“…[14][15][16][17][18][19][20][21][22][23][24][25][26] These three chiral building blocks can be prepared via a lipase-mediated desymmetrization of σ-symmetrical diol 20, [27][28][29][30] a diastereoselective conjugate addition of a methyl group to 22, and Lewis acid (LA)-mediated diastereoselective Claisen rearrangement of 24, respectively, and have been converted successfully to helianane allelochemicals 31) (Chart 1).…”