Application of the lithiation–borylation reaction to the rapid and enantioselective synthesis of the bisabolane family of sesquiterpenes
作者:Varinder K. Aggarwal、Liam T. Ball、Simon Carobene、Rickki L. Connelly、Matthew J. Hesse、Benjamin M. Partridge、Philippe Roth、Stephen P. Thomas、Matthew P. Webster
DOI:10.1039/c2cc32176a
日期:——
The expedient enantioselective synthesis of 5 bisabolane sesquiterpenes has been achieved using a common, one-pot lithiation-borylation reaction of secondary benzylic carbamates and either protodeboronation or oxidation to give the natural products in fewer than 5 steps, with high yield and >94 : 6 er.
Harnessing the Power of the Asymmetric Grignard Synthesis of Tertiary Alcohols: Ligand Development and Improved Scope Exemplified by One-Step Gossonorol Synthesis
作者:Saranna E. Kavanagh、Declan G. Gilheany
DOI:10.1021/acs.orglett.0c02629
日期:2020.11.6
A series of N-substituted cyclohexyldiaminophenolic ligands for the asymmetric Grignard synthesis of tertiary alcohols is reported. The 2,5-dimethylpyrrole-decorated ligand led to improved enantioselectivities and broadened the scope of the methodology. As an exemplar, we report an unprecedented highly selective one-step synthesis of gossonorol in 93% ee, also constituting the shortest formal syntheses
Enantioselective synthesis of (+)-gossonorol and related systems using organozinc reagents
作者:Susana González-López、Miguel Yus、Diego J. Ramón
DOI:10.1016/j.tetasy.2012.04.003
日期:2012.4
The sesquiterpene (+)-gossonorol is prepared in only three synthetic steps in 60% overall yield and 82% ee from commercially available reagents. The key asymmetric step is the catalytic enantioselective addition of dimethylzinc to 5-methyl-1-(2-methylphenyl)hex-4-en-1-one catalyzed by chiral isoborneolsulfonamide ligands in the presence of titanium tetraisopropoxide. The modular approach allows the synthesis not only of the aforementioned natural product but also other products arising from the corresponding processes of ethylation, phenylation, and ethynylation, just by changing the final nucleophilic reagent and using the same isoborneol type ligand. (C) 2012 Elsevier Ltd. All rights reserved.