A Short Asymmetric Synthesis of Sauropunols A–D

Synthesis ◽  
2017 ◽  
Vol 49 (13) ◽  
pp. 2939-2942 ◽  
Author(s):  
Tibor Gracza ◽  
Martin Markovič ◽  
Peter Koóš
Keyword(s):  
Asymmetric Synthesis ◽  
Asymmetric Epoxidation ◽  
Sharpless Asymmetric Epoxidation

A short and efficient asymmetric synthesis of natural sauropunols A, B, and C/D has been accomplished in 6 steps from divinylcarbinol with overall yield of 19%, 7% and 32%, respectively. The key synthetic steps include effective Sharpless asymmetric epoxidation of penta-1,4-dien-3-ol and a highly diastereoselective Pd-catalysed oxycarbonylation of pentene-1,2,3-triol. The structures of sauropunols A and B have been confirmed.

Facile synthesis of the enantiomers of frontalin

1984 ◽  
Vol 62 (11) ◽  
pp. 2148-2154 ◽  
Author(s):  
B. D. Johnston ◽  
A. C. Oehlschlager
Keyword(s):  
Asymmetric Epoxidation ◽  
Facile Synthesis ◽  
Epoxidation Reaction ◽  
Synthetic Sequence ◽  
Sharpless Asymmetric Epoxidation

S-(−)- and R-(+)-frontalin (1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane) were prepared from (E)-2-methyl-2,6-heptadiene-1-ol utilizing the Sharpless asymmetric epoxidation reaction to induce chirality. The six-step synthetic sequence proceeded in approximately 50% overall yield and was found to be suitable for the preparation of multi-gram quantities of either enantiomer with ≥ 90% ee.

Enantioselective Synthesis of 4-Amino-3-hydroxybenzopyran Flavanol Derivatives from Chalcones

Synthesis ◽  
2018 ◽  
Vol 50 (24) ◽  
pp. 4796-4808 ◽  
Author(s):  
Leslie Aldrich ◽  
Qiwen Gao ◽  
Lianyan Xu ◽  
Vincent Parise ◽  
Yash Mehta
Keyword(s):  
Biological Evaluation ◽  
Enantioselective Synthesis ◽  
Allylic Alcohol ◽  
Nucleophilic Aromatic Substitution ◽  
Asymmetric Epoxidation ◽  
Aromatic Substitution ◽  
Chemical Library ◽  
Epoxy Alcohols ◽  
Sharpless Asymmetric Epoxidation

A concise method that is easily amenable for analogue synthesis has been developed to enantioselectively access 4-amino-3-hydroxybenzopyrans from chalcones. Epoxy alcohols were formed from chalcones through a Corey–Bakshi–Shibata reduction of the enone and subsequent Sharpless asymmetric epoxidation of the allylic alcohol. The epoxy alcohols were protected, regioselectively opened with various amines using catalytic europium(III) triflate, and the resulting free alcohols were orthogonally protected. Concomitant deprotection and intramolecular nucleophilic aromatic substitution provided the benzopyran core, which is poised to undergo additional reactions to provide a diverse chemical library with ideal properties for biological evaluation.

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