Type H Syntheses

Type H (C—N—C + C—S) Syntheses.—In the course of their detailed studies of nitrile-ylides, Huisgen and his co-workers have examined cycloadditions of benzonitrile 4-nitrobenzylide (27) [arising from N-(4-nitro-benzyl)benzimidoyl chloride, (26 Ar = P-C6H4NO2)] to a variety of carbon-heteroatom multiple bonds. Thus, the interaction of (26) with em excess of methyl dithiobenzoate in triethylamine gave 85% yields of 2,5-diphenyl-4-(4-nitrophenyl)thiazole (29), with loss of methanethiol, two stereoisomeric A -thiazolines (28) being formed intermediately. The same thiazole arose by the use of monothiobenzoate from the primarily formed 5-methoxythiazoline (30) by spontaneous loss of methanol.  

The cycloaddition of (27) to dimethyl trithiocarbonate occurs readily in the cold in a direction opposite to that of (di)thiobenzoates, yielding (31) the 

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Type H Syntheses of Thiazoles (S—C + C-N-C). Base-induced cycloadditions of tosylmethyl isocyanide (4-MeC6H4S02CH2NC) and an isothiocyanate RNCS (R = alkyl, allyl, PhCO, aryl, etc.) have been investigated. Depending on the reaction conditions, thiazoles (91) and/or imidazoles (92) are obtained. A high-yield ring-transformation of (91) to (92) occurs in THF/ BuLi. ... 

Type H Syntheses (S-C + C-N-C). Isothiocyanates (RNCS) and methyl isocyanoacetate react, in THF containing Bu0 , to form thiazoles (83 R=Me,Et,Bu,cyclohexyl,benzyl,Ph,4-ClCgH, R1=Me) in 53-77 yield. Some (83) were saponified to corresponding carboxylic... 

Type H Syntheses (Se-C + C-N-C). Selenazoline selones (172 X=Se) result from the reaction of CSe2 with 2-substituted dimethylamino-azirines (171 R =Me,Et,R2=Ph). With 2,2-dimethylazirine (171 R =R2=Me) the zwitterionic selenazoline (173) is formed. The latter exists as the isoselenocyanate in solution. Reactions from both forms occur. Ho05 oxidation of (172 R1=Me,Et,X=Se) gives selenazolinones (172 R = Me,Et,X=0). CSe2 combines with... 

Here, we have taken advantage of the low silanol content in pure silica LTA and CHA type zeolites synthesized in fluoride medium to get better resolved 29Si and H solid state NMR spectra in the silanol region. This has allowed us to investigate the nature of the silanol groups in zeolites and their interaction with water molecules. 

Two type la syntheses of (3-hydroxypyrroles have appeared. An aza-Nazarov cyclization of l-azapenta-l,4-dien-3-ones produced (3-hydroxypyrroles including 2,2 -bipyrroles <06EJO5339>. A second approach to a (3-hydroxypyrrole involved an intramolecular N-H insertion into a rhodium carbene derived from the decomposition of a diazoketone <06JOC5560>. On the other hand, the photochemical decomposition of the diazoketone led to pyrrolidin-2-ones. 

Hansel, R., Rimpler, H. and Langhammer, L. (1966a) IR-Spektren der a-pyrone vom yangonin-und kawain-type und synthese von 4-methoxy-5,6-dihydro-6-methyl-pyron-2 als modellsubstanz. Zeitschrift fur Analytische Chemie, 218, 346—353. 

Type F Syntheses of Thiazoles (C-N-C-S + C). Substituted 7V-thiocarba-molyformamidines R CSN=CR NMe2 react with allyl bromide to give an azavinamidinium salt, which, upon treatment with a base, gives an ethylidene-A -thiazoline (R = = Me2N R = H, R = morpholino). This last com-... 

Type F Syntheses (C-N-C-S + C). Enaminothiones, RCSN=CR2NR R3 (R=substituted amino,R2=H,Me,Et,NMe2,R =R2=Me,Et R1=H, R2=Ph,Me) react with ArCH-X or alkyl/arylCOCH5X (X=halogen) to form vari-... 

Type G Syntheses (N-C-S-C-C). Various 2,4,5-trisubstituted thi-azoles have been prepared in good yield from thiocyanates R COCHR SCN (R2,R =H,alkyl,Ar,alkoxycarbonyl, acyl.benzoyl) and active methylene compounds CH-RR (R.R rCN, HCO,N00,alkanoyl,... 

Synthesis. - Type C Syntheses (C-C-H-C + S). Imines prepared from aldehydes and t NCR CR R X (X=leaving group,R1,R, R3,R =H, alkyl,Ar) react with S donors such as Na2S to form the corresponding thiazolidines (152)1. ... 

Type Syntheses (S-C-N-C-C). Cyclisation of (158) to 2-arylimino-thiazolidines (159 R=aIkyl,alkylthio,alkenyl,cyclopropyl,Ph,PhO, PhNHCO,halogen,R, R =H,alkyl,halogen or ring) occurs with HCl/H O ... 

Synthesis. - Type A Syntheses (S-C H -N + C). The C-nucleoside (182) is formed by condensation of 2-amino-4-chlorobenzenethiol with an acetylated aldonic nitrile or glycosyl cyanide followed by deacetylation23. 2-Aminobenzenethiol reacts with RC0CsCPh(Rs2-thienyl) to give (183). The latter cyclises to 2-phenylbenzo-thiazole on attempted recrystallisation (MeOH). With terminal acetylenic ketones a mixture of benzothlazolines results232. 

Type E Syntheses N—C — C—S + C). The reaction between ketones RCOCH2R (R = pentyl, hexyl, etc.), ethyleneimine, and sulphur gives a mixture of 2,2-dialkylated thiazolidines and 5,6-dihydrothiazines, but only the former products are obtained when HSCH2CH2NH2 is used. A combination of the azirines (79 R = H R = H or alkyl) or (79 R R = Me), 2-hydroxy- or 2-dimethyIamino-tetrahydropyran, and hydrogen sulphide produces 2-(4-hy-droxybutyl)-thiazolidines (80). ... 

Work on thienothiopyrans of various types continues. Syntheses have been reported for the following compounds (91), (92 R = H or Me) and... 

Taguchi, H. Yamasaki, S. Yosinaga, A. I. M. et al. CO oxidation on perovskite-type LaCoOs synthesized using ethylene glycol and citric acid. Catal. Commun. 2008, 9, 1913-1915. 

Type B Syntheses (C—C—N + C—S).—Thiocyanation of oi -unsaturated jS-amino-ketones R3HNCRi=CHC(0)R2 (Ri = Me or Ph R= = Me, Ph, or OEt R = H, Me, or Ph) with cyanogen occurs at the olefinic H-atom, or gives a 2-imino-A -thiazoline, or its rearranged isomer (8), depending upon the structure of the starting material and reaction temperature. The thiocyanated alkenes are cyclized to mixtures of the cyclized products in acid or alkali, or else thermally. 

Type K Syntheses (C—C—N—C—S).—1,2-Dichloroethyl isothiocyanate reacts with thioureas to give thiadiazines, at room temperature, or thiazoles (11) at 80—100 °C. The former rearrange to the latter on heating or in the presence of base. With ureas, the only ureido-derivative isolated corresponded to (11 Ri = H, R = R = Me). ... 

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