Thiazole groups

The first empirical and qualitative approach to the electronic structure of thiazole appeared in 1931 in a paper entitled Aspects of the chemistry of the thiazole group (115). In this historical review. Hunter showed the technical importance of the group, especially of the benzothiazole derivatives, and correlated the observed reactivity with the mobility of the electronic system. In 1943, Jensen et al. (116) explained the low value observed for the dipole moment of thiazole (1.64D in benzene) by the small contribution of the polar-limiting structures and thus by an essentially dienic character of the v system of thiazole. The first theoretical calculation of the electronic structure of thiazole. benzothiazole, and their methyl derivatives was performed by Pullman and Metzger using the Huckel method (5, 6, 8). 

Conversion of the thiazole group in (353b) into the formyl group leads to compound (354). Additional transformations gave compounds (355) and (356) (Scheme 2.154) (214, 215). 

The most important contact allergen in the thiazole group is mercaptohenzothiazol (MBT). 2 Studies thus far suggest that men are more often affected than women. ... 

Formyl anion equivalent. This reagent can be used as the equivalent of the formyl anion. Thus it reacts with an aldehyde such as 2 in the absence of a catalyst to form mainly the anti-adduct. After protection of the hydroxy group, the thiazole group can be converted to a formyl group by N-methylation, reduction, and hydrolysis. 

Of the many specific types of oxazoles, those bearing a 4-carboxy-derived group are of considerable importance. Among these compounds are several natural products, including many which contain this moiety, or the analogous thiazole group. 

Thiazolylalanine itself gave good enantioselectivity of up to 60-70% ee and poor to mediocre yield of 10-40%. Placing the thiazole group at the C-terminus of the short peptide chain reduced the enantioselectivity of the reaction, but the nature of the C-terminus amide played no major role. Significant improvement of yield (up to 67%) under retention of enantioselectivity (65-80%) could be achieved, when the thiazolylalanine group was incorporated into the middle of a short peptide chain [24,32]. The reaction depicted in Figure 6.6 could then be carried out with 13 5% yield and ees of about 70%. 

A mixture of oleic acid, cremophor EL, and ethanol solubilizes 100 mg of ritonavir in Norvir soft gelatin capsules. Ritonavir is an HIV protease inhibitor with a peptide-like structure that has an intrinsic water solubility of 1.0 pg/mL and two weakly basic thiazole groups with pKa s of 1.8 and 2.6, which preclude... 

Thiamin contains a substituted thiazole group which is involved in the decarboxylation of pyruvate by pyruvate decarboxylase. Thiamin occurs in cells largely as its active coenzyme form thiamin pyrophosphate (TPP) (Fig. 7.14). 

Mechanism of action of transketolase (only the thiazole group of thiamin pyrophosphate is shown). 

Hosomi and coworkers described the cross-coupling reaction between arylsilanes or heteroarylsilanes and aryl halides mediated by a copper(I) salt. In particular, the cross-coupling reaction of 2-TST (1) with iodobenzene under fluoride- and palladium-free conditions (eq 31) was examined employing different solvents and copper(I) salts (Table 1). The yield of the product was increased in polar solvents such as 1,3-dimethyl-2-imidazolidinone (DMI). In addition, it was found that the reaction was best promoted by CuOCgFs because of the strong affinity of pentafluorophenoxide ion to the silicon atom, resulting in an accelerated transfer of the thiazole group to copper. 

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