2‐benzothiazolyl phenacyl sulfoxide,a new precursor for 2‐oxo‐2‐phenylethanethial

Previously, a facile formation of a thioaldehyde by the thermolysis of a heteroaryl phenacyl sulfoxide was confirmed by the detection of a cycloadduct with 2,3‐dimethyl‐1,3‐butadiene. The usefulness of benzothiazolyl phenacyl sulfoxide as a precursor for 2‐oxo‐2‐phenylethanethial was studied under the same conditions in the presence of various dienes and anthracene. In all cases, the Diels‐Alder cycloadducts were formed in moderate to good yields, and the addition of triethylamine as external base was revealed to be effective for carrying out the thermolysis under milder reaction conditions and for the improvement of yields. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 363–367, 1999