Formal Benzannulation via Pyrylium Intermediates

TransiUon-Metal-Mediated Ammatic Ring Construction, First Edition. Edited by Ken Tanaka. 2013 John Wiley Sons, Inc. Published 2013 by John Wiley Sons, Inc. 

1 Gold Catalyst The gold-catalyzed formal [4-1-2] benzannulation reaction was reported by use of o-alkynylbenzaldehydes 11 and alkynes 2 in the presence of a catalytic amount of AuXs (X = Cl, Br), and the corresponding a-naphthyl ketones 

Panda et al. demonstrated the synthesis of quinolines 17 and isoquinolines 18 with this method by the use of pyridine-containing oxoalkynes [12]. 

Treatment of 11 with alkynes 2 in the presence of excess amounts of CUCI2 resulted in the formation of a-chlorinated naphthalenes 24 in good to high yields 

CeHis R = H, Et, Ph, P-CH3C6H4, P-CH3OC6H4, P-FC6H4. C5H11 

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