The Addition of Dienes to Coumarin and to Certain Substituted

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C O N T R I B U T I O N PROM THE N O Y E S CHEMICAL

LABOLYIOKY, ~TNIV!3RSrTVOF

ILLINOIS]

The Addition of Dienes to Coumarin and to Certain Substituted Cinnamic Acids. I. BY ROGERADAMS,W. D. MCPHEE,R. B. CARLINAND 2. W. WICKS I t has been demonstrated by Sugasawa, Kodama and Harala and by Fujise, Horiuchi and TakahashiIb that 2,3-dimetliq.l-l,R-butadiene will add to cinnamic acid, ethyl cinnamate, or cin namic aldehyde to form a partially hydrogenated biphenyl carboxylic acid, its ester, or correspondiiig aldehyde.

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0 11 in. p. 181"

t

CHj I

1

R is COOH, COOEt, or CHO

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'These structures were written in analogy t o the 0 earlier work of Diels and Alder.2 The possible 111 application of this reaction to the synthesis of isomeric dimethylbutadiene adducts (IV) were partially hydrogenated dibenzopyrones required subjected to demethylation with hydrobromic in another investigation has led to the study of acid in acetic acid a t the reflux temperature, and the addition of dienes to coumarin, to o-hydroxy- both yielded the same corresponding hydroxy cinnamic acid, and to several o-methoxycinnamic acid (VI). This hydroxy acid was not dehydrated acids. successfully to the pyrone although a variety of Numerous attempts to bring about the addition conditions was used. Therefore, i t probably of dienes to coumarin, which would yield directly has the structure shown in VIa At 180°, with hydrogenated dibenzopyrones, failed CHa under normal conditions. The reaction i/ \ CH=CHCOOH --j (/----\--\ ? J was finally accomplished in the case OCH3 OCH3 COOH of 2,3-dimethyl-l,3-butadiene, but not v t n . p. 199" m. p. 147" with butadiene or isoprene, by using a large excess of reagent and a temperaCHa ture of 260'. The pyrone (11) was ( 7 .q.;: .formed in poor yield. trans-o-Hy - '- C H--+ OCH

> - nL C 5 H l l ( n )-+ d COOCH, OCH,

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1'1

OCH I1 CHJ OCH, l3,CC-j -=CHI COOH OzE, .

.-.... ..

111

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(1) Adams, M c P h e e , Carlin and \ricks 'lais j t J U K N A I . , 66, :4.i (1943). (2) Adams. Wolff, C a i n and Clark. ibzd., 62, l77(l , l!34ll~ r : i J I3r A . A .4lbert 1,rivate communication 11

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