Diastereoselective Control Through Hydrogen Bonding in the Aziridination of the Chiral Allylic Alcohols by Acetoxyaminoquinazolinone

2009 ◽  
Vol 74 (24) ◽  
pp. 9452-9459 ◽  
Author(s):  
Murat Cakici ◽  
Semistan Karabuga ◽  
Hamdullah Kilic ◽  
Sabri Ulukanli ◽  
Ertan Şahin ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Allylic Alcohols

An Apparent Stereochemical Effect in MnO2 Oxidation of Some Allylic Alcohols

1971 ◽  
Vol 49 (18) ◽  
pp. 3038-3045 ◽  
Author(s):  
Bert Fraser-Reid ◽  
Bernard J. Carthy ◽  
N. L. Holder ◽  
Mark Yunker
Keyword(s):  
Hydrogen Bonding ◽  
Manganese Dioxide ◽  
Hydroxyl Group ◽  
Allylic Alcohols ◽  
Unsaturated Ketone ◽  
Anomeric Effect ◽  
Chair Form ◽  
Large Separation ◽  
Acid Catalyzed

3,4-Di-O-acetyl-D-xylal undergoes acid-catalyzed reaction with ethanol to give the anomeric mixture of ethyl 2,3-dideoxy-4-O-acetyl-D-glycero-pent-2-enopyranosides which can be separated after deacetylation. The α-D anomer 1 is readily oxidized by manganese dioxide to the α,β-unsaturated ketone but the β-D anomer 2 is inert. Thorough investigation of the 100 and 220 MHz n.m.r. spectra of 1 and 2, their acetates, and dinitrobenzoates indicates that each exists conformationally pure in the half-chair form having the benefit of the anomeric effect. Hence in the oxidizable anomer 1 the C-4 allylic hydroxyl group is pseudo-equatorial; in the unoxidizable one it is pseudoaxial. Hydrogen bonding does not appear to be the reason for failure of 2 to oxidize.The ethoxy groups of 1 and 2 are found to be ABX3 system with unusually large separation for the AB protons.

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