Vilsmeier-Haack protocol

Aromatic nitriles, including thiophenes, can be accessed through a Vilsmeier-Haack protocol followed by the addition of iodine and aqueous ammonia. Benzothiophene (not shown) was found to be unreactive in this system. The authors theorized that this was possibly due to insufficient electron density. ... 

The bicyclic ketal 62 incorporates the intact C(3)-C(10) portion of the backbone of the erythromycin antibiotics, and its construction was viewed as the first objective. In the event, this undertaking was initiated with the straightforward formylation of commercially available 2-ethylfuran (64) according to the Vilsmeier-Haack protocol to provide 65 (Scheme 9). The diastereoselective... 

The known intermediate 6-bromo-2-chloroquinoline-3-carbaldehyde (17) was prepared from 4-bromoacetamilide using a modified Vilsmeier-Haack protocol. Homer-Wadsworth-Emmons olefmation of 17 with the lithium enolate of phosphonate (Et0)2P(0)CH2C02Et afforded a,P-unsaturated ester 18 in 89% yield with complete E-selectivity. 

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