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The chemistry of coumarin derivatives, part 2. Reaction of 4‐hydroxycoumarin with α,β‐unsaturated aldehydes
Author(s) -
Appendino Giovanni,
Cravotto Giancarlo,
Tagliapietra Silvia,
Nano Gian Mario,
Palmisano Giovanni
Publication year - 1990
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19900730709
Subject(s) - chemistry , coumarin , 4 hydroxycoumarin , alkyl , adduct , chromone , benzopyran , organic chemistry , stereochemistry , catalysis
4‐Hydroxycoumarin (= 4‐hydroxy‐2 H ‐1‐benzopyran‐2‐one) reacts with enals to give 1,2‐ or 1,4‐addition products, depending on the nature and relative location of the substituents on the olefinic double bond ( Scheme 2 ). The resulting adducts further react intra‐ or intermolecularly, affording dimeric coumarins or pyranocoumarins in the case of 1,2‐addition and acetalic pyranocoumarins in the case of 1,4‐addition. With enals bearing alkyl groups at C(β), 2 H ‐pyrano[3,2‐ c ]coumarins are the only products formed, and the reaction represents an easy and straightforward entry into this class of recently described biologically active natural products.