Pulvinic permethylated

Olefination reactions of the phosphonates (254) and (255) derived from hydantoin and 1-methylhydantoin, respectively, provide good yields of the expected C-5 unsaturated hydantoin derivatives (256), generally as mixtures of isomers. 52 Heterocyclic analogues, e.g. (257), of pulvinones and, e.g. (258), of permethylated pulvinic acids have been synthesized by Wadsworth-Emmons reactions of the phosphonates (259) and (260), themselves prepared directly from substituted maleic anhydrides. 55 The reaction of ylide (261) with aldehydes to give (262) has been used as a key... 

Patenden et al. [46] synthesized heterocyclic analogues of pulvinones 52-55 and of permethylated pulvinic acids 56, 57 which were found in higher fungi (Scheme 21). All compounds possessing lactonic structures were synthesized in the Horner-Wittig reaction using the corresponding heteroaryl aldehydes and 4-dimethoxy-phosphorylated lactone 58. The latter was obtained as the main product in the reaction between substituted maleic anhydrides 59 and sodium dimethyl phosphite via the postulated carbene. 

Dehydration. British chemists have developed a total synthesis of un-symmetrical pulvinic acid pigments of lichens and fungi. The method is illustrated for the synthesis of the permethylated derivative of gomphidic acid (4), the... 

The postulated chemotaxonomic link between Sclerodermataceae and Boletales is further strengthened by the detection of sclerocitrin-D (141), a terphenylquinone analogue of the naphthalenoid pulvinic acids, in Scleroderma citrinum (250). The pigment has been isolated in the form of its yellow nonamethyl derivative by permethylation of the complex mixture of closely related pigments which are to be found... 

Scheme 1. Alkaline degradation pf permethylated pulvinic acids...

In 1975, Pattenden etal. reported the first regiospecific synthesis of permethylated pulvinic acids 46 [48] and pulvinones 45 [49] by condensation of 44 with aroyl formates and aryl aldehydes, respectively, followed by dehydration (Scheme 1.5). Interestingly, Pattenden s pioneering work allowed the first total synthesis of naturally occurring pulvinones, first isolated from natural sources in 1973 [3b] but... 

Knight, D. W., and G. Pattenden Syntheses of Permethylated Derivatives of Pinastric Acid and Gomphidic Acid, Pulvinic Acid Pigments of Lichen and Fungi. J. Chem. Soc. (London) Perkin Trans. I 1979, 84. 

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