Structure reassignment of the major isomer from the Diels-Alder reaction of acryloyl chloride and 4,5,6,6a-tetrahydropentalene

1998 ◽  
Vol 76 (9) ◽  
pp. 1289-1293
Author(s):  
M Parvez ◽  
A Rauk ◽  
T S Sorensen ◽  
F Sun
Keyword(s):  
Carboxylic Acid ◽  
2D Nmr ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acryloyl Chloride ◽  
X Ray ◽  
Diels Alder Reaction ◽  
Major Isomer ◽  
Facial Selectivity ◽  
Final Proof

After hydrogenation and hydrolysis, the two adducts formed from the Diels-Alder reaction of acryloyl chloride and 4,5,6,6a-tetrahydropentalene were originally assigned 7-exo- and 7-endo-carboxylic acid structures 3 and 4. Based on unexpected results in using these acids as starting materials for a superacid carbocation study, a reinvestigation of these structural assignments was carried out. From an extensive series of 2D NMR experiments, we conclude that 4 is correctly assigned, but that the other isomer is the 9-endo carboxylic acid 8. The formation of these two isomers (out of eight possible modes of addition) can be rationalized. Finally, an X-ray study of 8 was carried out as a final proof of structure.Key words: Diels-Alder reaction, facial selectivity, regioselectivity, X-ray structure, MO calculation.

Angucyclinones Related to Ochromycinone. IV. The Structures and Reactions of Unusual Diels-Alder Adducts Formed from Maleic Anhydride and Racemic 5,5-Dimethyl-3-vinylcyclohex-2-en-1-ol

2000 ◽  
Vol 53 (5) ◽  
pp. 403 ◽  
Author(s):  
Craig Brinkworth ◽  
Tomas Rozek ◽  
John H. Bowie ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Carboxylic Acid ◽  
Maleic Anhydride ◽  
Anticancer Activity ◽  
Alder Reaction ◽  
Major Product ◽  
Diels Alder ◽  
Epoxide Ring ◽  
X Ray ◽  
Osmium Tetraoxide ◽  
Diels Alder Reaction

The Diels–Alder reaction between maleic anhydride and racemic 5,5-dimethyl-3-vinylcyclohex-2-en-1-ol gives two racemic diastereomers, the major product (2a,S,3R,8aS,8bR)-7,7-dimethyl-2-oxo-2a,3,4,6,7,8,8a,8b-octahydro-2H-benzo[cd]isobenzofuran-3-carboxylic acid (63% yield), and the minor product (2aR,3S,8aS,8bS)-7,7-dimethyl-2-oxo-2a,3,4,6,7,8,8a,8b-octahydro-2H-benzo[cd]isobenzofuran-3-carboxylic acid (9%). Epoxidation of the major product gives racemic (1aS,3R,3aS,5aR,8aS,8bR)-7,7-dimethyl-4 oxoperhydro-benzo[cd]oxireno[2,3-e]isobenzofuran-3-carboxylic acid in 81% yield, while opening of the epoxide ring gave the trans diol (2aS,3R,5S,5aR,8aR,8bR)-5,5a-dihydroxy-7,7-dimethyl-2-oxoperhydrobenzo[cd]isobenzofuran-3-carboxylic acid in 58% yield. Treatment of the major Diels–Alder product with osmium tetraoxide gave the cis diol (2aS,3R,5S,5aR,8aS,8bR)-5,5a-dihydroxy-7,7-dimethyl-2-oxoperhydrobenzo[cd]isobenzofuran-3-carboxylic acid in 86% yield. The structures of four products were confirmed by X-ray and n.m.r. methods. None of the products exhibit anticancer activity.

An ab Initio Study of Facial Selectivity in the Diels−Alder Reaction

1998 ◽  
Vol 63 (1) ◽  
pp. 105-112 ◽  
Author(s):  
James D. Xidos ◽  
Raymond A. Poirier ◽  
Cory C. Pye ◽  
D. Jean Burnell
Keyword(s):  
Ab Initio ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ab Initio Study ◽  
Diels Alder Reaction ◽  
Facial Selectivity
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