ChemInform Abstract: New Coumarin Derivatives: 2‐(N‐R‐Imino)‐2H‐1‐benzopyrans.

Abstract

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Synthesis and electronic spectra of 3‐hetaryl substituted coumarin derivatives 7‐hydroxy‐2H‐chromen‐2‐on and 9‐hydroxy‐2H‐benzo(f)chromen‐2‐on

“…Later, Pechmann and Welsh [23] found that a coumarin derivative is formed when a mixture of phenol and malic acid is heated in the presence of concentrated sulphuric acid. In most cases, the synthesis of 2‐iminocoumarins is based on the Knoevenagel reaction between o ‐hydroxybenzaldehydes and aromatic or heteroaromatic compounds bearing a cyanomethyl substituent in the presence of organic bases [24–26]. This type of reaction is used mainly for preparation of 3‐substituted coumarins.…”

Synthesis of novel 3‐hetaryl‐substituted 6‐ and 8‐hydroxybenzo[f]coumarin derivatives

“…Relatively few synthetic methods afford good yields of coumarin moieties. To synthesise 2‐iminocoumarins, the Knoevenagel reaction, between ortho ‐hydroxybenzaldehydes and a nitrile with an activated methylene group in the presence of organic bases, is the most common reaction [11–13]. This type of reaction is more often used to prepare other substituted coumarins.…”