New Enantioselective Synthesis of (10R,11S)-(+)-Juvenile Hormones I and II
摘要:
The (10R,11S)-(+)-juvenile hormones I (1) and II (2) were synthesized by Sharpless asymmetric dihydroxylations of methyl (2E,6E, 10E)-7-ethyl-3, 11-dimethyl-2,6,10-tridecatrienoate (4) and methyl (2E,6E,10E)-3,7,11-trimethyl-2,6,10-tridenoate (5), respectively, as the key steps.
Vibsatin A is a new neurotrophic vibsane-type diterpenoid comprising a bridged bicyclo[4.2.1]nonane skeleton. Inspired by Sawamura’s works, we generated the bicyclic backbone through a Conia-ene-derived 7-exo-dig cyclization from an enantiomerically enriched TIPS-based silyl enol ether. The reaction, catalyzed by a sensitive gold(I) complex, was efficiently performed on a large scale by glovebox free
Investigations towards the synthesis of xylindein, a blue-green pigment from the fungus Chlorociboria aeruginosa
作者:Christopher D. Donner、Anthony N. Cuzzupe、Cheryl L. Falzon、Melvyn Gill
DOI:10.1016/j.tet.2012.02.009
日期:2012.4
An approach towards the synthesis of the fungal pigment xylindein 1 is described. Synthesis of the pyranonaphthoquinone corresponding to one half of the xylindein framework is achieved over 11 steps from 1,2-epoxypentane, utilizing multiple Diels–Alder cycloaddition processes. Methods for self-coupling of dihydroxynaphthoquinones to give extended quinones are explored.
Catalytic asymmetric Corey-Chaykovsky epoxidation of ketones with dimethyloxosulfoniummethylide 2 using an LLB 1a + Ar3P O complex proceeded smoothly at room temperature, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (91-97%) and yield (>88-99%) from a broad range of methyl ketones with 1-5 mol % catalyst loading. The use of achiral additive Ar3P O 5i was important