A regio and diastereoselective transformation of 3-dienyl-2-azetidinones to novel pyrroloxazine

The regioselective nitroso Diels–Alder (NDA) cycloadditions of 3-dienyl-2-azetidinones with nitrosobenzene to generate oxazine-substituted β-lactams in excellent yields are reported. The amidiolytic ring opening of the cycloadducts with sodium methoxide followed by iodocyclization using I2/K2CO3 etiquette to capitulate previously unknown, multisubstituted pyrroloxazine in outstanding yields is also accounted.