Ethyl orthoformate homologation

Ethyl orthoformate homologation - The special ability of the [Ru(CO)3X3] species for activating oxygenated substrates is also well evidenced by the homologation of ethyl orthoformate at lower temperatures ( 130 - 170 °C) (18). 

Furthermore, the homologous complex 286 condenses with ethyl orthoformate to give, in the course of a new y-tropolone synthesis, tropolone ether 287 by O-ethylation it is transformed to tropylium salt 288 (Scheme 72 70JA6382) the corresponding tropone complex was synthesized from dibenzotroporic and Cr (CO)6 [83AG(S)734]. 

In the earliest example of this type of reaction,58 2-amino-5-methyl(N-p-tolyl)benzylamine and triethyl orthoformate were heated at 100°C for 1 hr to furnish a good yield of 6-methyl-3-p-tolyl-3,4-dihydroquinazoline (see l).58 The same authors obtained the 2-methyl homolog by substituting ethyl acetimidate (in boiling benzene) for the ortho ester. 

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