Stereoselective Intramolecular Hetero Diels–Alder Reactions of Cyclic Benzylidenesulfoxides and DFT Calculations on the Transition Structures

✍ Scribed by Lutz F. Tietze; Thomas Pfeiffer; Ansgar Schuffenhauer

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 214 KB
• Volume: 1998
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199812)1998:12<2733::aid-ejoc2733>3.0.co;2-c

✦ Synopsis

The 4-benzylidene-3-oxo[1,3]oxathiolan-5-ones 13-15, calculations (B3LYP/6-311+G*) using the model systems 28 and 29. In addition B3LYP/6-31G*//B3LYP/3-21G ( * ) which were derived from the 3-oxo[1,3]oxathiolan-5-ones 9-11 by Knoevenagel condensation with the aldehydes 12, calculations on transition structures for the hetero Diels-Alder reaction of 29 and 30 allowed a good correlation with cyclize in an intramolecular hetero Diels-Alder reaction with high yield and excellent endo/exo as well as induced the experimental results, which show that an endo attack of the dienophile syn to the S-O group in 13-15 leads to the diastereoselectivity to give the hetero Diels-Alder adducts 16-18. The preferred formation of the Knoevenagel products main products. 13-15 with a (Z) configuration was predicted with DFT