17O NMR Spectroscopy of Sulfolenes (2, 5-Dihydrothiophene-1,1-dioxides) and Sultines (3, 6-Dihydro-1,2-oxathiin-2-oxides)-Experiment and Quantum Calculations: Synthesis of 4, 9-Dioxo-1,2-oxathiacyclodecane-2-oxide, a New Heterocycle
✍ Scribed by Elena Roversi; Frédéric Monnat; Kurt Schenk; Pierre Vogel; Pedro Braña; José A. Sordo
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 220 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
The products of hetero-Diels ± Alder reactions (sultines) and cheletropic addition reactions (sulfolenes) between 1,3-dienes and sulfur dioxide can be distinguished by their 17 O NMR shifts. Experimental data have been collected for derivatives of 3,6dihydro-1,2-oxathiin-2-oxide and of 2,5dihydrothiophene-1,1-dioxide. This data was then compared with that calculated by the gauge independent atomic orbital (GIAO) method at the HF/6-31 G(d,p) and HF/6-311 G(3df, 2p) levels of theory with geometries optimized by MP2/6-31G(d) calculations. GIAO-MBPT(2) calculations were also performed with the 6-31 G(d,p) basis set. The adduct between (E)-1-methoxybutadiene and SO 2 is sulfolene 3, the ozonolysis of which in SO 2 followed by work-up with ethanol provided (2RS,3SR,6SR)-( 31), (2RS,3RS,6SR)-(32), and (2RS,3RS, 6RS)-2,6-diethoxy-3-methoxy-1,4-oxathiane-4,4-dioxide (33). Single-crystal X-ray diffraction studies are reported for 32 and 33. Ozonolysis of the hetero-Diels ± Alder adduct of SO 2 with 1,2-dimethylidenecyclohexane produced 4,9-dioxo-1,2-oxathiacyclodecane-2-oxide (34), the first member of a new class of sulfur heterocycles. Keywords: ab initio calculations ćycloadditions ´NMR spectroscopy ´ozonolysis ´sulfur heterocycles was consistent with the fact that the cheletropic additions usually require temperatures above À 60 8C in order to take place. Furthermore, quantum calculations [8] suggested that sultine 2 can be as stable as sulfolene 3 because of a stabilizing thermodynamic anomeric effect (gem-disubstitution effect of [a] Prof.