Preparation of functionalized heteroaromatics using an intramolecular Wittig reaction.

The development of efficient methods for the synthesis of heteroaromatic compounds is always of great importance for chemists. In this 'Perspective', we describe a general approach for the synthesis of functionalized heteroaromatics via intramolecular Wittig reactions. In all cases, the reaction proceeds via in situ generated phosphorus ylides. We especially emphasize the importance of chemoselective intramolecular Wittig reactions using designed Michael acceptors and suitable acyl chloride as trapping reagents, which allows formation of two different classes of heteroaromatics from the same substrates. This metal-free approach is quite general and works in a number of examples, furnishing the corresponding products in moderate to good yields under relatively mild reaction conditions.