
TY  - JOUR
A1  - Varelis, Peter 
A1  - Johnson, Brian L. 
T1  - A General and Diastereoselective Approach to the Preparation of <emph type="2">cis</emph>-2,6-Disubstituted Pyrans
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1997
VL  - 50
IS  - 1
SP  - 43
EP  - 52
KW  - 
UR  - https://doi.org/10.1071/C96095 
N2  - The utility of preparing cis-2,6-disubstituted 5,6-dihydro-2H-pyrans by the methodology implied in Scheme 1 is demonstrated through the preparation of the two pyrans (1) and (2). The overall yields for the two nine-step sequences starting from the enals (3) and (4) were 57 and 54%, respectively, whilst the overall diastereochemical yield approached 100%. The key features of the method are (i) a highly regioselective Lewis acid-catalysed cyclocondensation reaction of a nucleophilic diene with an aldehyde to afford a 2,3-dihydro-4H-pyran-4-one, (ii) reduction of a pyranone with better than 98% regio- and stereo-chemical control to give the corresponding glycal, and (iii) an ester enolate Claisen rearrangement of a glycal acetate. 
ER  -

