Photosensitized oxygenation of some benzyl sulfides. The role of persulfoxide

S. M. BONESI, M. FRECCERO, A. ALBINI

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

Johm Wiley and Sons Ltd.

Lugar: EEUU; Año: 1999 vol. 12 p. 703 - 707

0894-3230

ABSTRACT: Benzyl ethyl sulfide (6a) is photo-oxidized to benzaldehyde in benzene, whereas diethyl sulfide is known to give inefficiently the sulfoxide under these conditions. Oxidative C—S cleavage is the main process also with benzhydryl ethyl sulfide (6c), but not with a-methylbenzyl ethyl sulfide (6b), which mainly gives the sulfoxide. The carbonyl derivatives reasonably arise from S-hydroperoxy ylides (3). Consistently with this finding, calculations at the PM3 level suggest that the first intermediate, the persulfoxide (1), undergoes intramolecular hydrogen transfer when an activated a-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidation6a) is photo-oxidized to benzaldehyde in benzene, whereas diethyl sulfide is known to give inefficiently the sulfoxide under these conditions. Oxidative C—S cleavage is the main process also with benzhydryl ethyl sulfide (6c), but not with a-methylbenzyl ethyl sulfide (6b), which mainly gives the sulfoxide. The carbonyl derivatives reasonably arise from S-hydroperoxy ylides (3). Consistently with this finding, calculations at the PM3 level suggest that the first intermediate, the persulfoxide (1), undergoes intramolecular hydrogen transfer when an activated a-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidation6c), but not with a-methylbenzyl ethyl sulfide (6b), which mainly gives the sulfoxide. The carbonyl derivatives reasonably arise from S-hydroperoxy ylides (3). Consistently with this finding, calculations at the PM3 level suggest that the first intermediate, the persulfoxide (1), undergoes intramolecular hydrogen transfer when an activated a-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidationS-hydroperoxy ylides (3). Consistently with this finding, calculations at the PM3 level suggest that the first intermediate, the persulfoxide (1), undergoes intramolecular hydrogen transfer when an activated a-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidation1), undergoes intramolecular hydrogen transfer when an activated a-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidationa-hydrogen is available and gives 3. This is the case for the above benzyl sulfides (DH¹ for the process decreases with decreasing C—H BDE). However, only some of the persulfoxide conformations are correctly oriented for this rearrangement, and this may slow this process and make other reactions compete, as happens with 6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidation6b. Copyright Ó 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidationÓ 1999 John Wiley & Sons, Ltd. KEYWORDS: single oxygen; sulfides; photochemistry; oxidation