| Abstract
| - 3,4-Dihydro-2-methoxy-5-methyl-2H-pyran and3,4-dihydro-2-methoxy-5,6-dimethyl-2H-pyran undergo addition−rearrangement reactions with arylsulfonyl isocyanatesto generate the corresponding3-formyl- and3-acetyl-6-methoxy-3-methyl-1-(arylsulfonyl)-2-piperidones. Forexample, 3,4-dihydro-2-methoxy-5-methyl-2H-pyran and phenylsulfonyl isocyanateafforded 3-formyl-6-methoxy-3-methyl-1-(phenylsulfonyl)-2-piperidone as a separable trans/cis mixture in highyield. The more reactivephenoxysulfonyl and alkoxysulfonyl isocyanates provided analogousresults.
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