Phenothiazin-3-ones

C. verticillata -acetylphenothiazine sulfoxide phenothiazine sulfoxide phenothiazin-3-one phenothiazine N-glucoside ... 

An aqueous solution of the antihistamine, promethazine (361) hydrochloride, was photolysed to promethazine sulphoxide, phenothiazine, phenothiazine sulphoxide and 3//-phenothiazin-3-one (362) [206]. 

Phenoxazin-3-ones and phenothiazin-3-ones can be prepared by condensation of 2-aminophenols or -thiols with quinones. Alizarin Green G (61), for example, is obtained from (59) and (60). Similarly, 2-aminothiophenols and 6-chloro-2-methoxy-l,4-benzoquinone (62) afford phenothiazin-3-ones (63). 

Other isolated products consist of the 3H-phenothiazine-3-one derivatives B (13), C and D ( 11), the formation of which may be explained by a radical hydroxylation of PT . 

Since superoxide reduces readily quinoid structures (e.g. B) (14), product C (7-hydroxy-3H-phenothiazine-3 one) may have a similar genesis, and 7-(10-phenothiazinyl)-3H-phenothiazine-3-one (D) represents one of the many possible recombination products starting from PT . 

Benzophenone (BP) sensitized photooxidation of phenothiazine leads mainly to the formation of products A and B (17). In view of the many data available from the literature and from our own experiments the published interpretation needs, however, some revision provided 3H-phenothiazine-3-ones are not products of a singlet oxygen reaction with ground state phenothiazine (c.f. methylphenothiazine), formation of products A and B implies two different oxidation mechanisms. Since singlet oxygen sensitization by benzophenone (Equations 10 to 12) is known to be very inefficient, reaction sequence (10), (13), (14), and (9)... 

There have been reports of various phenothiazine and phenoxazine anion-radicals which are species which correspond to structure 244 and its substituted derivatives. Thus, reduction of phenothiazin-3-one in... 

Ito and his coworkers have reported that palladium-catalyzed oxidative coupling reactions of Grignard reagents in the presence of V-substituted isocyanide dichloride afford diynes (equation 17). Isocyanide dichloride may serve as a reoxidant of the palladium catalyst in this sequence via a catalytic cycie. In addition Kiji and his coworkers have described the oxidative coupling of phenylacetylene by a Pd-Cu catalyst in the presence of 4-iodo-(3//) phenothiazin-3-one. ... 

There have been reports of various phenothiazine and phenoxazine anion-radicals which are species which correspond to structure 244 and its substituted derivatives. Thus, reduction of phenothiazin-3-one in DMF gives 259 for which hyperfine splittings are indicated in gauss. The assignment of splittings was made following study of halogenated derivatives of 259 and McLachlan MO calculations. Similar anions from phenoxazin-... 

Oprean and Schaefer (72LA(765)1) have used protected 2-aminobenzenethiols 86 and 3-acetyl or 3-methoxy-carbonyl-2,5-dimethoxy-l,4-benzoquinones 87 to synthesize 2-hydroxy-3H-phenothiazin-3-ones 89 (Scheme 41). The reaction intermediate is 3-amino-1,4-benzoquinone 88A whose tautomer 88B undergoes dehydration under acid catalysis to provide the final compound 89. 

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