Methyl 4,G-O-benzylidene-2-be1izylthio-2-deosy-or-~-altropyranoside and methyl l,(j-0-benzylidene-3-benzylthio-3-deoxy-or-~-altropyraosid have been prepared by the reaction of sodi~tlu benzylmercaptide with methyl 3,3-anhyclro-4,G-O-be11zylidene-a-n-allopyratoide and methyl 2,3-anhydro-4,6-0-benzylidene-a-~-1nan11opyra11oside respectively.These two thio ethers were successfully reduced by sodium in l i q~~i d ammonia to methyl ~-deoxy-2-t11ercapto-or-~-altropyranoside and methyl 3-deosy-3-tnercapto-or-D-altropyranoside. A n attempted replacement of the tosyl group in 1,2;5,U-cli-0-isopropylidene-:M-tosyl-or-~-glucofuranose by benzyl mercaptan was uns~~ccessful. INTRODUCTIOSThe preparation of non no saccharides in which an oxygen atom has been replaced by a sulphur atom has received renewed attention in recent years, primarily due to the fact that these co~npounds provide a route to the synthesis of deoxy sugars. A review by Raymond covering the literature on thio sugars to 1944 (1) refers t o the preparation of a number of thioglycosides and w-deoxy-w-alkylthio-hexoses and -pentoses. The only monosaccharide mentioned which contained a free mercapto group on a carbon atoll1 other than the anomeric carbon ( 2 4 ) was a substance clescribed as "3-deoxy-3-mercapto-D-glucose" obtained by Freudenberg and Wolf (5) in their attempt t o apply the Tschiigaeff reaction (6) to the preparation of an unsaturated monosaccharide.Since 1944, a considerable amount of work has appeared in this area, but primarily concerning the preparation of the thioglycosides and thio ethers of monosaccharides (7-12). A few reports have been ~n a d e of the preparation of monosaccharides with a free nlercapto group. An improved synthesis of 1-thio-D-glucose by the reaction of hydrogen sulphide with l,2-anhydro-D-glucose and its 3,3,G-tri-0-acetate in dimethylformamide has been clescribed (13). The reduction with lithium aluminum hydride of 5,G-dideoxyd,G-epithio-l,2-O-isopropylicle1~e-~-~-iclose has yielded 5,0-dideoxy-5-mercapto-L-idose (14). There has also been reported the preparation of 5,G-clideoxy-1,2-0-isopropylidene-5,G-(t11iocnrbonyldithio)-p-L-idose, a compound wi~ich, no doubt, can be reduced readily to 5,G-dideoxy-1,2-O-isopropylidene-5,G-climercapto-~-~-idose with lithium alumini~m hydride in accordance with similar reductions carried out on the trithiocarbonates of seine hexitols (14,15).Since a number of mercapto monosaccharicles were required in this laboratory, a program for their preparation was begun. This paper presents some results obtained in this direction. RESULTS .ASI> DISCGSSIOSThe debenzylation of S-benzylcysteine has been accomplished by the use of sodiunl in liquid ammonia (lG) and this technique has been successfully applied in this laboratory to the preparation of ~nercaptoindoles (17). These results suggested that mercapto monosaccharides might be prepared by the reaction of beilzyl mercaptan with suitable anhydro monosaccl~arides followed by the reductive cleavage of the resulting benzylthio ethers with sodium in...

The photochemical reactions of 4,4'-bis(pheny1azo)biphenyl and 4-phenylazoazobenzene in 98% sulphuric acid have been examined, for comparison with the corresponding reactions in 2 2~ acid. Photochemical cyclodehydrogenation of 4-phenylazoazobenzene to two benzo[c]cinnoline derivatives has thereby been effected for the first time. The observed course of the latter reaction has led, in turn, to studies of the benzidine rearrangement of 2-(2-phenylhydrazino)benzo[c]cinnoline, of the photochemical cyclodehydrogenation of 3-phenylazobenzene, and of the photochemical reaction of 2-phenylazobenzo[c]cinnoline. The results of these investigations are now recorded and discussed.It has been known for some time that azobenzene (I), on being irradiated in 2 2~ sulphuric acid, forms a mixture of benzo[c]cinnoline (11) and benzidine (111) in approximately equivalent quantities.l.2 Under these conditions the reaction appears to be largely an intermolecular disproportionation process, in which cyclodehydrogenation of a given quantity of azobenzene to benzo[c]cinnoline is accompanied by reduction of an equal quantity of the same compound to hydrazobenzene. Hydrazobenzene has not been detected, as such, in any of the reaction mixtures, but it is obviously the precursor of the isolated benzidine.

The mass spectra of quinoline N-oxides,l pyridine N-oxides,2 and Al-pyrroline N-oxides2 have been reported. Although M-0 ions are of diagnostic value in some of the ~pectra,l3~ no skeletal rearrangement ions have been reported.

1,1'-, 1,2'-, 2,2'-Azonaphthalenes, and 2-phenylazonaphthalene are not cyclized photochemically under conditions in which azobenzene is converted into benzo[c]cinnoline and benzidine; but 1-phenylazonaphthalene has been shown to give naphtho[1,2-c]cinnoline, and 4-phenylazobenzene gave 2-phenylbenzo[c]cinnoline. Although 4-styrylazobenzene showed some evidence of cyclization, the reaction was extremely slow and was accompanied by considerable decomposition. 4-Phenylezoazobenzene was cleaved by sulphuric acid, and no cyclized product was obtained. Irradiation of 4,4'-bis(phenylazo)biphenyl gave two cleavage products, and two benzo[c]cinnoline derivatives. Simultaneous reduction and oxidation apparently occurred within the same molecule.

No abstract