Reimer-Tiemann reaction scope

While the Friedel-Crafts acylation is a general method for the preparation of aryl ketones, and of wide scope, there is no equivalently versatile reaction for the preparation of aryl aldehydes. There are various formylation procedures known, each of limited scope. In addition to the reactions outlined above, there is the Vdsmeier reaction, the Reimer-Tiemann reaction, and the Rieche formylation reaction The latter is the reaction of aromatic compounds with 1,1-dichloromethyl ether as formylating agent in the presence of a Lewis acid catalyst. This procedure has recently gained much importance. 

The Reimer-Tiemann reaction used to be an important way of making ortho-substituted phenols, but the yields are often poor, and modern industly is wary of using large quantities of chlorinated solvents. On a small, laboratory scale it has largely been superseded by ortholithiation (Chapter 9) and by modern methods outside the scope of this book. The mechanism probably goes something like this. 

The amidomethyl group, which is readily introduced into even deactivated rings, can be oxidized via N-bromosuccinimide and hydrolysis to give the corresponding benzaldehyde in high yield.The use of phase-transfer catalysts significantly increases the yields in Reimer-Tiemann reactions.In a recent review on the uses of hexamethylenetetramine, the scope and utility of the Duff and Sommelet reactions are discussed (ca. 30 references). ... 

---

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

---