Isothiazoles spectra

The microwave spectrum of isothiazole shows that the molecule is planar, and enables rotational constants and NQR hyperfine coupling constants to be determined (67MI41700>. The total dipole moment was estimated to be 2.4 0.2D, which agrees with dielectric measurements. Asymmetry parameters and NQR coupling constants show small differences between the solid and gaseous states (79ZN(A)220>, and the principal dipole moment axis approximately bisects the S—N and C(4)—C(5) bonds. 

The IR spectrum of 8 has been reported (63FRP2166), and the UV spectra of some 1,2,3-benzothiadiazines have been reviewed (70CRV593). Mass spectrometry has been used to establish the structure of 1,2,3-thiadiazines 24, and the fragmentation pattern enabled the alternative isothiazol-N-imines to be ruled out (750MS579). 

The absolute configuration of the sulfur atom in 3-amino-substituted isothiazole A-oxides (see Section 4.05.5.5) was obtained by theoretical calculation of the ECD spectrum and comparison with the experimental ECD curve (see Section 4.05.2.1) <2006UP1>. 

Isothiazole derivatives manifest a broad spectrum of useful properties and have applications in several fields. Several examples were reported in CHEC(1984) <1984CHEC(6)131>, CHEC-II(1996) <1996CHEC-II(3)319>, and other reviews <2002RCR673, 2002AHC(83)71, 2002SR279, 2002SR79, 2007THC(9)179>. 

The negative ion mass spectrum of isothiazole has been studied in detail <92Mi 305-01 >. A main conclusion from a study of collision-induced activation and charge reversal negative ion spectra of isothiazole and its 3-, 4-, and 5-methyl derivatives is that reaction with NH2 gives rise to depro-... 

Gleiter and coworkers64 have studied a number of planar heteroaromatic systems involving S—N bonds within the ring structure. Thieno[3,4-c]isothiazoleis a nonclassical condensed thiophene, and its triphenyl derivative, triphenylthieno [3,4-c] isothiazole (106), is a 1071 system containing two different masked 1,3-dipolar systems. It was synthesized from 4-phenyl-1,3,2-oxathiazolylium-5-olate (104) and dibenzoylacetylene via the direct precursor isothiazole (105) and its photoelectron spectrum compared with that of the related thieno [3,4-c] thiophene (107)34. The spectrum is characterized by an isolated first band at 6.9 eV which is verified by PPP-CI calculations to involve the 7c( au ) orbital confined to the thienothiophene ring. 

Thieno[2,3-e]isothiazoles. - Reaction of ethyl 3-cyano-5,5-di-ethoxy-2-oxopentanoate with P2S5 in refluxing toluene gives a monoacid, C NO, in 24 yield. The N.M.R. spectrum and unambiguous synthesis showed thi3 to be thieno[2,3-cJisothia-zole-3-carboxylic acid (44) and not the isomeric thieno[3,4-d]-isothiazole (45) as previously suggested. Cyclisation to... 

Sulphoximines have also been employed for the synthesis of four- and five-membered ring structures containing the sulphoximine unit (Scheme 7). The jS-lactam (38) shows an abnormally low C=0 stretching frequency (1690 cm ), attributed to the contribution of a dipolar structure +S—N=C—0 , or to an expanded N—C—C bond angle, or both. The isothiazole derivative (39) exists in the enolic form its u.v. spectrum is... 

A very detailed study of the i.r. and Raman spectra of isothiazole has appeired, providing reasoned assignments of the observed spectral features. The work included the preparation of 4- and 5-monodeuterio-and 4,5-dideuterio-isothiazoles, and their study from this point of view. The analysis of the Raman spectrum of isothiazole required the modification of the assignment of two of the fundamental modes previously given for this parent compound. Not the least useful aspect of this paper is the extensive list of references to the subject which it provides. 

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