O-17 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
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 O-17 NMR shifts. Experimental data have been collected for derivatives of 3,6-dihydro-1,2-oxathiin-2-oxide and of 2,5-dihydrothiophene-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 SO2 is sulfolene 3, the ozonolysis of which in SO2 followed by work-up with ethanol provided (2RS,1SR,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 SO2 with 1,3-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 ; cycloadditions ; NMR spectroscopy ; ozonolysis ; sulfur heterocycles ; Nuclear-magnetic-resonance ; spin coupling-constants ; sulfur-dioxide ; diels-alder ; homocheletropic additions ; shielding tensors ; chemical-shifts ; stereoselective synthesis ; c-13 ; competition
Univ Lausanne, Chim Sect, BCH, CH-1015 Lausanne, Switzerland. Univ Lausanne, Inst Cristallog, BSP, CH-1015 Lausanne, Switzerland. Univ Oviedo, Lab Quim Computac, Dept Quim Fis & Analit, Oviedo, Principado de A, Spain.
Record created on 2005-11-09, modified on 2016-08-08