5-Benzothiazolyl derivatives

Goto et al. (386) have qualitatively studied the relationship between the structure and the ease of formation of some 2-aryl- and 2-heteroaryl-A-2-thiazolin-4-one derivatives. It is found that 2-pyridyI, 2-benzimidazoyl, and 2- 6 hydroxy-5 -methyl)-benzothiazolyl derivatives are too unstable to be isolated. 6 -Hydroxy-, 6 -methyl-, and unsubstituted 2-benzothiazoiyl derivatives, as well as naphtothiazolyl derivatives are unstable but isolable. On the other hand, 6 -methoxy-. 6 -acetoxy-. and 5, 7 -dimethyl-6 -hvdroxybenzothiazolyl derivatives as well as most of their 5-methyl substituted derivatives are stable and easily prepared. 

Thiazolyl and benzothiazolyl derivatives are known for their anti-inflammatory, analgesic, and antipyretic activities [72-77], for example Meloxicam (Fig. 3) is a known non-steroidal anti-inflammatory agent with a thiazolyl... 

Ferrieres and Plusquellec described the synthesis of per-acetylated S-benzothiazolyl galactofuranosides from P-D-galactofuranose pentaacetate in the presence of BFs-EtaO in 83% yield as an anomeric mixture (52, 55). The obtained thioimidates were then deprotected and applied in anomeric phosphorylation. A number of acylated S-benzothiazolyl and S-(5-methoxy)benzothiazolyl derivatives of D-gluco, D-galacto, and D-ribofurano series have been reported by Khodair et al (34). While the syntheses of hexoses were accomplished from acetobromosugar and the corresponding sodium thiolates in MeCN, the synthesis of thioribofruunoside derivative was accomplished from ribofiiranose tetraacetate and trimethylsilylated thiols in the presence of TMSOTf (34). 

In connection with an investigation of the fluorescent characteristics of derivatives of 2,2 -bithienyls, a number of heterocyclic substituted thiophen derivatives, such as (199)—(204) and their formyl derivatives, have been prepared. The quinoline derivatives were obtained from the appropriate 2-lithiobithienyl and quinoline, whereas the benzimidazolyl, benzoxazolyl, and benzothiazolyl derivatives were prepared by the condensation of a cyanothiophen or 5-cyano-2,2 -bithienyl with the appropriate aniline derivative. (204) was prepared through a Fischer indole synthesis. ... 

Reaction of the diphosphine ligand R2P(CH2)2PR2 (R = benzothiazolyl) (L) with [RhCl(PPh3)3] gives the exclusively P-coordinated product [RhCl(PPh3)(L)] (88JOM(338)C31, 92JCS(D)241), which is perhaps a common feature of the P-substituted derivatives of oxazole and thiazole. 

Af-(2,3-Dihydroimidazo[2,l-6]benzothiazol-6-, 7- and 8-yl)aminomethy-lenemalonates (1474, R2 = H) were alkylated with dialkyl sulfate or alkyl halide in hexamethylphosphortriamide in the presence of sodium hydride to give N-alkyl-N-(2,3-dihydroimidazo[2, l-fe]benzothiazolyl)aminomethy-lenemalonates (1474, R2 = H). The hydrolysis of1474 by heating in boiling dilute hydrochloric acid for 15 min gave alkylamino derivatives (1475) (81EUP21806). 

Anodic regioselective fluorination of a-phenylsulphenylated ethyl acetates, 1-naphthalene and 2-pyridine derivatives [80], l-aryl-3-(phenylthio)oxindoles and 2-substituted-3-oxo-4-(phenylthio)-l, 2, 3,4-tetrahydroisoquinolines [81], 2-benzo-thiazolyl and 5-chloro-2-benzothiazolyl sulfides [82], a-(phenylsulfenyl)lactams [83], as well as various heterocycles such as thiolanones, oxathiolanones, dithi-olanones, 3Fl-l,4-benzoxathian-2-ones [84] in Et3N-3HF or Etr NF- HF [n = 3,4), has been reported. 

For an example of glycoside synthesis with 0-benzylated 2-benzothiazolyl-1-thio-D-gluco-pyranoside in the presence of Cu(OTf)2, see T. Mukaiyama, T. Nakatsuka, and S. Shoda, An efficient glucosylation of alcohol using 1-thioglucoside derivative, Chem. Lett. p. 87 (1979),... 

In the presence of base, N-(2-benzothiazolyl)benzohydrazonoyl bromides 23 [72JCS(P1)1519] suffer elimination of hydrogen bromide to yield benzothiazolo[2,3-c]-1,2,4-triazole derivatives 148. Also, the action of base on the hydrazonoyl bromides 22 caused their conversion to 1-phenyl-8-bromoimidazo[l,2-6]-s-triazolo[3,4-/]pyridazine 149 (67T387). 

The synthesis and biological activity of 2,4,6-triamino-substituted-1,3,5-tiiazines have been described <03JIC138>. The synthesis of //-substituted 2,4-diamino-6-(benzothiazolyl-2-thiomethyl)-l,3,5-triazines 11 has been achieved from guanidine derivative 9 through intermediate 10 <03KGS730>. 

Benzothiazolyl alkyl sulfides, prepared from the corresponding alcohols, are easily desulfurized (87-99%) by TBTH-AIBN. This reaction constitutes a good indirect deoxygenation of alcohols. Desulfurization of dithioketals may be controlled. Thus 1,3-dithiolanes with 1 mol equiv. of TBTH lead to 3-alkyl (or 3-aryl) thiols (64-82%), while 4 mol equiv. of TBTH leads to the completely desulfurized derivative. Desulfurization of heterocyclic thiones is also performed with this reagent. In passing, it should be noted that generation of radicals from C—S bonds and tin hydrides in the presence of radical initiators is of large synthetic interest. ... 

Many hydrazone derivatives have been proposed as spectrophotometric reagents for Co, namely 2,2 -dipyridyl-2-pyridylhydrazone (e = 4.2-10 ), 2-furaldehyde-2-pyridylhydrazone [79], benzil-2-pyridylketone-2-pyridylhydrazone [80], and 2,2 -dipyridyl-2-benzothiazolyl-hydrazone [81]. Co was determined in the presence of Hg [82], and in the presence of Ni [83] by the derivative spectrophotometry using benzil-2-pyridylketo-2-quinolylhydrazone. 

The Julia-Julia coupling reaction has been extended to sugar derived lactones to furnish methylene exoglycals in good yields as exemplified by the conversion of lactone 188 to exomethylene derivative 190 upon treatment with lithiomethyl benzothiazolyl sulfone from 189 <05SL520>. This approach serves as an alternative to the Tebbe reagent commonly used... 

Of the urea derivatives containing the benzothiazolyl group as substituent two compounds are used in agriculture benzthiazuron, I-(benzothiazol-2-yl)-3-methylurea (43) (Hack et ai, 1966) and methabenzthiazuron, l-(benzothiazol-2-yl)-3,3-dimethylurea (44) (Searle, 1956 Hack et al, 1967 Hack, 1968). The former is selective in sugar beet and spinach, the latter in cereals, pea, bean and other crops. 

Kozikowski et al utilized the AgBF4-activated reaction " of the protected 4-[(2-benzothiazolyl)-thio]epicatechin (121) with the similarly protected procyanidin B-2 derivative (122) to form a mixmre of tri-through octa-mers (123)-(128) (Scheme 19). This mixture was readily separated by HPLC using a Waters... 

Malichenko, N. A. Yagupol skii, L.M. Delta-(2-Benzothiazolyl)perfluorovaleric acid and its derivatives. Zh. Obshch. Khim. 1969, 39(8), 1751-1755. 

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