Abstract
The C2-symmetric vinyl sulfoxide, trans-2-methylene-1,3-dithiolane 1,3-dioxide, was found to react with a range of 3-oxidopyridinium betaines (bearing different substituents on nitrogen) in high yield and with total diastereoselectivity. A 2.3 : 1 mixture of regioisomers was formed with all of the 3-oxidopyridinium betaines but the ratio was found to change over prolonged periods of time due to reversibility of the minor regioisomer. 3-Oxidopyridinium betaines bearing methyl substituents at either the 2- or 6-position were also tested in the cycloaddition process. Improved regioselectivity ( 8 : 1) and again high diastereoselectivity were observed with the betaine having an additional substituent at the 2- position, but with betaines having a substituent in the 6-position although high regioselectivity was observed (9.9 : 1), the major isomer was formed with low diastereoselectivity (5.5 : 4.4). The origin of the regio- and diastereo-selectivity with all the betaines is discussed. Finally, the C2-symmetric vinyl sulfoxide, trans-2-methylene-1,3-dithiolane 1,3-dioxide was reacted with an oxidopyrylium betaine in moderate yield. Good regioselectivity and moderate diastereoselectivity were observed.
Original language | English |
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Pages (from-to) | 1884-1893 |
Number of pages | 10 |
Journal | Organic and Biomolecular Chemistry |
Volume | 1 |
Issue number | 11 |
DOIs | |
Publication status | Published - 13 May 2003 |
Keywords
- CHIRAL KETENE EQUIVALENT
- L-GLUTAMIC ACID
- GONG-TENG-A
- ENANTIOSELECTIVE SYNTHESIS
- (1R,3R)-2-METHYLENE-1,3-DITHIOLANE 1,3-DIOXIDE
- ENANTIOSPECIFIC SYNTHESIS
- ASYMMETRIC-SYNTHESIS
- CYCLO-ADDITION
- (+)-FERRUGININE
- NITRONES