(4 + 2) Cycloaddition of Ketenes and β-Methoxy α,β-Unsaturated Ketones: 2-Pyranones

Article abstract of DOI:10.1021/jo00174a034

The cycloaddition of diphenyl- and various chloroketenes to β-methoxy α,β-unsaturated ketones afforded (4 + 2) cycloaddition products.The cycloadducts resulting from the chloroketenes were converted to 2-pyranones on treatment with zinc in moist acetic acid.The cycloaddition products from chloroketenes and β-(methoxymethylene)-α-tetralone were readily converted to substituted benzocoumarins.