Neat carbomethoxypivaloylketene - preparation and chemical reactivity

Neat carbomethoxypivaloylketene, the first fairly persistent alpha -oxokete ne stabilized both electronically as well as sterically, is generated by fl ash vacuum pyrolysis of the corresponding furan-2,3-dione. It adds primary amines to afford pivaloyl-malonic acid amides and undergoes hetero-Diels-Al der reactions to furnish usual and unusual [4+2] adducts. Some stereo- and regiochemical features are verified with aid of 2D NMR experiments and a X- ray structure analysis. (C) 2001 Elsevier Science Ltd. All rights reserved.