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Stereoselective Intramolecular Hetero Diels–Alder Reactions of Cyclic Benzylidenesulfoxides and DFT Calculations on the Transition Structures
Author(s) -
Tietze Lutz F.,
Pfeiffer Thomas,
Schuffenhauer Ansgar
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199812)1998:12<2733::aid-ejoc2733>3.0.co;2-c
Subject(s) - knoevenagel condensation , intramolecular force , chemistry , diels–alder reaction , transition state , adduct , yield (engineering) , computational chemistry , stereoselectivity , medicinal chemistry , stereochemistry , organic chemistry , catalysis , thermodynamics , physics
The 4‐benzylidene‐3‐oxo[1,3]oxathiolan‐5‐ones 13 – 15 , which were derived from the 3‐oxo[1,3]oxathiolan‐5‐ones 9 – 11 by Knoevenagel condensation with the aldehydes 12 , cyclize in an intramolecular hetero Diels–Alder reaction with high yield and excellent endo/exo as well as induced diastereoselectivity to give the hetero Diels–Alder adducts 16 – 18 . The preferred formation of the Knoevenagel products 13 – 15 with a ( Z ) configuration was predicted with DFT calculations (B3LYP‐6‐311+G*) using the model systems 28 and 29 . In addition B3LYP‐6‐31G*/sB3LYP/3‐21G (*) calculations on transition structures for the hetero Diels–Alder reaction of 29 and 30 allowed a good correlation with the experimental results, which show that an endo attack of the dienophile syn to the S–O group in 13 – 15 leads to the main products.