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Enantioselective Synthesis of 2‐(2‐Arylcyclopropyl)glycines: Conformationally Restricted Homophenylalanine Analogs
Author(s) -
Demir Ayhan S.,
Sesenoglu Özge,
Ülkü Dincer,
Arici Cengiz
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490000
Subject(s) - chemistry , furan , enantioselective synthesis , diastereomer , stereoselectivity , cyclopropanation , yield (engineering) , ring (chemistry) , stereochemistry , medicinal chemistry , organic chemistry , catalysis , materials science , metallurgy
Starting from simple aromatic aldehydes and acetylfuran, ( E )‐1‐(furan‐2‐yl)‐3‐arylprop‐2‐en‐1‐ones ( 2 ) were synthesized in high yields. Cyclopropanation of the CC bond with trimethylsulfoxonium iodide (Me 3 SO + I − ) furnished (furan‐2‐yl)(2‐arylcyclopropyl)methanones 3 in 90–97% yields. Selective conversion of cyclopropyl ketones to their ( E )‐ and ( Z )‐oxime ethers 5 and oxazaborolidine‐catalyzed stereoselective reduction of the CN bond followed by separation of the formed diastereoisomers, furnished (2‐arylcyclopropyl)(furan‐2‐yl)methanamines 6 in optically pure form and high yield. Oxidation of the furan ring of ( S , S , S )‐, ( S , R , R )‐, ( R , S , S )‐, and ( R , R , R )‐ 6a afforded the four stereoisomers of α ‐(2‐phenylcyclopropyl) glycine ( 1a ).