Divergent Enantioselective Synthesis of (−)-Galanthamine and (−)-Morphine
作者:Barry M. Trost、Weiping Tang、F. Dean Toste
DOI:10.1021/ja054449+
日期:2005.10.1
tricyclic intermediate is available in six steps from 2-bromovanillin and the monoester of methyl 6-hydroxycyclohexene-1-carboxylate. This intermediate requires only two steps to convert to (-)-galanthamine. Using a Heck vinylation, we found that the fourth ring of codeine/morphine could be formed. The final ring formation involves a novel visible light-promoted hydroamination. Thus, six steps are required
Direct Catalytic Enantioselective Benzylation from Aryl Acetic Acids
作者:Patrick J. Moon、Zhongyu Wei、Rylan J. Lundgren
DOI:10.1021/jacs.8b11390
日期:2018.12.19
We demonstrate that metal-catalyzed enantioselective benzylation reactions of allylic electrophiles can occur directly from aryl acetic acids. The reaction proceeds via a pathway in which decarboxylation is the terminal event, occurring after stereoselective carbon-carbon bond formation. This mechanistic feature enables enantioselective benzylation without the generation of a highly basic nucleophile
Unique catalysis of gold nanoparticles in the chemoselective hydrogenolysis with H2: cooperative effect between small gold nanoparticles and a basic support
Gold nanoparticles on hydrotalcite act as a heterogeneous catalyst for the chemoselective hydrogenolysis of various allylic carbonates to the corresponding terminal alkenes using H2 as a clean reductant. The combination of gold nanoparticles and basic supports elicited significantly unique and selective catalysis in the hydrogenolysis.
Pd(0)-Catalyzedallylations of 4(5)-nitroimidazole, 1, 2-methyl-4(5)-nitroimidazole, 2, 4(5)-bromo-imidazole, 7, 4(5)-methoxyimidazole, 10, 5(6)-nitrobenzimidazole, 16a, 5(6)-methylbenzimidazole, 16b, benzotriazole, 19, and 5(6)-methylbenzotriazole, 22, were studied under several reaction conditions. Nitroimidazoles 1 and 2 were regioselectively allylated under thermodynamic control, leading to 1-allyl-4-nitro
Development of Aliphatic Alcohols as Nucleophiles for Palladium-Catalyzed DYKAT Reactions: Total Synthesis of (+)-Hippospongic Acid A
作者:Barry M. Trost、Michelle R. Machacek、Hong C. Tsui
DOI:10.1021/ja050340q
日期:2005.5.1
The ability to use aliphatic alcohols as competent nucleophiles in the palladium-catalyzed dynamic kinetic asymmetric transformation of Baylis-Hillman adducts is explored. High yield and enantioselectivity is obtained for both the kinetic transformation and dynamic kinetic transformation. The absolute stereochemistry of the products is used to explore the reactive conformation of 2-substituted pi-allyl