1-Vinyl-3,4-dimethoxybenzene

Leptolejeunea elliptica (Jungermanniales) grown on the leaf of higher plants emits an intense mold-like odor. This odor is caused by -ethylanisole (662) 136, 268). 1-Vinyl-3,4-dimethoxybenzene (663) has been obtained from Conocephalum conicum as a minor component 126). Dimethyl eugenol (665) is the major component of Marchesinia species 45, 129). 

Reagents and Conditions a) 1,2-dimethoxybenzene, H or Lewis acid, 83% b) AgNOs, MeOH, then H or reflux, 66% c) LiAlH4, THF, 67% d) methyl vinyl ketone, 93%. 

Synthetic work on the mesembrane group will no doubt be further stimulated by reports on their central nervous system activity and somewhat surprising biosynthesis. An interesting asymmetric synthesis of unnatural (+ )-mesembrine (38) has been announced (Scheme 4). The key intermediate (35), prepared in nine steps from 1,2-dimethoxybenzene, was treated with L-proline pyrrolidide (36) under conditions typical for the preparation of enamines. The product was not isolated but subjected to reaction with methyl vinyl ketone followed by acid treatment to give the cyclohexenone (37) in 38 % overall yield. The last step in the synthesis [(37) — (38)] was based on previous synthetic work on mesembrine alkaloids. The synthetic (+ )-mesembrine (38) was shown to exhibit a positive Cotton effect and thus an antipodal relationship to natural (— )-mesembrine. The mesembrine analogues (40 = H or OMe, = H, Me, or CHjPh) have... 

Intermolecular reaction of l-iodo-2,3-dimethoxybenzene (134) with the vinyl bromide 140 (10 equiv.) gave a mixture of 141 and 142 [37]. In this reaction, oxidative addition of 140 to the palladacycle 143 generates 144, and the coupled product 145 is formed by reductive elimination. Finally 5-exo cyclization of 145 and -H elimination afford 141. 

Valerolactone see Oxan-2-one Valeronitrile see Pentanenitiile Veratrole see 1,2-Dimethoxybenzene Vinyl acetate see Vinyl ethanoate Vinylbenzene... 

Aromatic hydrogen exchange in 1,3-dimethoxybenzene Hydrolysis of ethyl vinyl ether... 

A highly electrophilic phosphite gold(I) catalyst was applied to the intramolecular allene hydroarylation reaction to give a vinyl-substituted carbocycle [17], This cyclization proceeds effectively in cases where the aryl groups are electron-rich arene nucleophiles. A dimethoxybenzene bearing an allene group furnished a vinyl-substituted tetralin derivative in 85% yield (Scheme 18.18). From the mechanistic... 

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