Vinyl acetate Diels-Alder adduct from

In the Mukaiyama aldol additions of trimethyl-(l-phenyl-propenyloxy)-silane to give benzaldehyde and cinnamaldehyde catalyzed by 7 mol% supported scandium catalyst, a 1 1 mixture of diastereomers was obtained. Again, the dendritic catalyst could be recycled easily without any loss in performance. The scandium cross-linked dendritic material appeared to be an efficient catalyst for the Diels-Alder reaction between methyl vinyl ketone and cyclopentadiene. The Diels-Alder adduct was formed in dichloromethane at 0°C in 79% yield with an endo/exo ratio of 85 15. The material was also used as a Friedel-Crafts acylation catalyst (contain-ing7mol% scandium) for the formation of / -methoxyacetophenone (in a 73% yield) from anisole, acetic acid anhydride, and lithium perchlorate at 50°C in nitromethane. 

Norbornanone is generally prepared from the Diels-Alder adduct of cyclopentadiene and vinyl acetate by hydrogenation, saponification, and oxidation with chromic acid in acetic acid solution. The present procedure, which gives higher over-all yields in fewer steps, makes use of the superior solvent, acetone, for mild chromic acid oxidations and of the observation that formate esters of secondary alcohols can be oxidized directly to ketones. ... 

Mehta and coworkers recently presented a synthesis of racemic deoxynojirimycin analogs and isofagomin analogs [21 lb,211c], starting from the Diels-Alder adduct of vinyl acetate to 5,5-dimethoxy-1,2,3,4-tetrachlorocyclopentadiene. 

Reactions. Vinyl-indoles give normal Diels-Alder products with tetracyano-ethylene, such as compound (339) from 1-methyl-3-vinylindole, but in the case of the 2-methyl derivative (340), steric hindrance causes formation of the cyclobutane adduct (341). Irradiation of 1,3-diacetylindole produces the dimer (342), as shown by X-xdiy crystallography. The arylazo-indoles (343) give products (344) of the semidine type on treatment with zinc and acetic anhydride. ... 

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