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High‐pressure [2 + 4]‐cycloaddition of dimethylmaleic anhydride to 3,4‐dimethoxyfuran; synthesis of dimethoxycantharidin preliminary communication
Author(s) -
Jurczak Jamisz,
Koz̀luk Tomasz,
Filipek Stanislaw,
Eugster Conrad Hans
Publication year - 1982
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.19820650332
Subject(s) - chemistry , maleic anhydride , steric effects , furan , cycloaddition , double bond , yield (engineering) , derivative (finance) , high pressure , diene , organic chemistry , catalysis , polymer , materials science , natural rubber , engineering physics , economics , financial economics , engineering , copolymer , metallurgy
As an active diene (more active than furan itself), 3,4‐dimethoxyfuran ( 1 ) affords with many dienophiles the respective cycloadducts in a high yield [2]. It has recently been found that under thermal conditions 1 easily reacts with maleic anhydride and its monomethyl derivative, but not with dimethylmaleic anhydride ( 2 ) [3]. This is probably due to steric hindrance resulting from the location of two methyl groups on the double bond of the dienophile. Since all Diels‐Alder reactions in particular those with steric hindrance are pressure‐sensitive [4]. we resolved to perform the title reaction under conditions of static high pressure.