PHOTOCHEMISTRY OF N-HYDROXYPYRIDINE-2 THIONE DERIVATIVES - INVOLVEMENT OF THE 2-PYRIDYLTHIYL RADICAL IN THE RADICAL-CHAIN REACTION-MECHANISM

被引:60
作者
AVELINE, BM [1 ]
KOCHEVAR, IE [1 ]
REDMOND, RW [1 ]
机构
[1] HARVARD UNIV,MASSACHUSETTS GEN HOSP,SCH MED,DEPT DERMATOL,WELLMAN LABS PHOTOMED,BOSTON,MA 02114
关键词
D O I
10.1021/ja00143a013
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The primary and subsequent photochemistry of four N-hydroxypyridine-2-thione esters has been investigated by laser flash photolysis (lambda(exc) = 355 nm). A simple, high-yield synthetic method is given for their preparation with high purity. UV irradiation of these ester compounds was shown to lead specifically to the formation of benzyl, diphenylmethyl, tert-butyl, and benzoyloxyl radicals in addition to the 2-pyridylthiyl radical. in all cases, the initial photoinduced nitrogen-oxygen bond cleavage was found to occur in high quantum yield (Phi(N-O) approximate to 0.5) The radical species generated by this process (2-pyridylthiyl radical and carbon-centered or oxygen-centered radicals) were characterized and their reactivity toward several radical scavengers has been studied. An efficient delayed depletion of the N-hydroxypyridine-2-thione esters was also observed, leading to overall bleaching quantum yields, (Phi(B1), close to unity. We have demonstrated that the delayed consumption of ground-state ester was due to the reaction of the 2-pyridylthiyl radical with its precursor, occurring with a rate constant, k(r), of 3-4 x 10(9) M(-1) s(-1). This reaction, hitherto never proposed, leads to the formation of 2,2'-dipyridyl disulfide and further release of propagating radicals.
引用
收藏
页码:9699 / 9708
页数:10
相关论文
共 52 条
[1]   NEW AND IMPROVED METHODS FOR THE RADICAL DECARBOXYLATION OF ACIDS [J].
BARTON, DHR ;
CRICH, D ;
MOTHERWELL, WB .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1983, (17) :939-941
[2]   GENERATION AND FATE OF NONDECARBOXYLATING ACYLOXY RADICALS DERIVED FROM THE PHOTOLYSIS OF ACYL DERIVATIVES OF N-HYDROXY-2-THIOPYRIDONE [J].
BARTON, DHR ;
RAMESH, M .
TETRAHEDRON LETTERS, 1990, 31 (07) :949-952
[3]   THE INVENTION OF RADICAL REACTIONS .18. A CONVENIENT SOLUTION TO THE 1-CARBON PROBLEM (R-CO2H-](R-CO2H)-C-13) [J].
BARTON, DHR ;
OZBALIK, N ;
VACHER, B .
TETRAHEDRON, 1988, 44 (12) :3501-3512
[4]   THE GENERATION AND REACTIVITY OF OXYGEN CENTERED RADICALS FROM THE PHOTOLYSIS OF DERIVATIVES OF N-HYDROXY-2-THIOPYRIDONE [J].
BARTON, DHR ;
JASZBERENYI, JC ;
MORRELL, AI .
TETRAHEDRON LETTERS, 1991, 32 (03) :311-314
[5]   RADICAL DECARBOXYLATIVE BROMINATION OF AROMATIC-ACIDS [J].
BARTON, DHR ;
LACHER, B ;
ZARD, SZ .
TETRAHEDRON LETTERS, 1985, 26 (48) :5939-5942
[6]   THE INVENTION OF NEW RADICAL CHAIN REACTIONS .8. RADICAL CHEMISTRY OF THIOHYDROXAMIC ESTERS - A NEW METHOD FOR THE GENERATION OF CARBON RADICALS FROM CARBOXYLIC-ACIDS [J].
BARTON, DHR ;
CRICH, D ;
MOTHERWELL, WB .
TETRAHEDRON, 1985, 41 (19) :3901-3924
[7]   INVENTION OF NEW REACTIONS USEFUL IN THE CHEMISTRY OF NATURAL-PRODUCTS [J].
BARTON, DHR ;
ZARD, SZ .
PURE AND APPLIED CHEMISTRY, 1986, 58 (05) :675-684
[8]   QUANTUM YIELDS IN THE PHOTOCHEMICALLY INDUCED RADICAL CHEMISTRY OF ACYL DERIVATIVES OF THIOHYDROXAMIC ACIDS [J].
BARTON, DHR ;
BLUNDELL, P ;
JASZBERENYI, JC .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1991, 113 (18) :6937-6942
[9]   THE INVENTION OF RADICAL REACTIONS .15. SOME MECHANISTIC ASPECTS OF THE DECARBOXYLATIVE REARRANGEMENT OF THIOHYDROXAMIC ESTERS [J].
BARTON, DHR ;
BRIDON, D ;
FERNANDEZPICOT, I ;
ZARD, SZ .
TETRAHEDRON, 1987, 43 (12) :2733-2740
[10]   GENERATION OF ALKOXY RADICALS FROM N-ALKOXYPYRIDINETHIONES [J].
BECKWITH, ALJ ;
HAY, BP .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1988, 110 (13) :4415-4416