Trehazolin synthesis isothiocyanate

Thus, the synthesis of trehazolin and its analogues required two precursors, the glycosyl isothiocyanate or amine analogues thereof, and trehazolamine or isothicya-nate analogues, respectively. 

Sugar derivatives having isothiocyanate groups on the various carbon atoms were used for the synthesis of trehazoline and its analogues. Thus, the glycosyl isocyanate, where the isothiocyanate group is at the anomeric center, as required for the synthesis of trehazolin 2, was readily synthesized by reaction of the glycosyl donor 6 with a metal isothiocyanate (Scheme 2).23... 

Toward a complete synthesis of trehazolin (2), 2,3,4,6-tetra-O-benzyl-1 -deoxy-z-D-glucopyranosyl isothiocyanate (7)52 was brought into reaction with the amines 5 and 374 in the presence of triethylamine to afford the x-D-glucopyranosyl thiourea derivatives 375 or 376, respectively (Scheme 46).38 Subsequent treatment with 2-chloro-3-ethylbenzoxazolium tetrafluoroborate and triethylamine afforded the corresponding amino oxazoline derivatives 377 and 378. Finally, hydrogenation over Pd(OH)2 on carbon afforded trehazolin (2). 

The synthesis of the bromodeoxy and epoxy analogues of trehazoline were achieved by reaction of the aminobromocyclopentitol 280 with glucosyl isothiocyanate 7 to give the thiourea 427 in 50% yield, which underwent cyclization by the action of yellow HgO to afford aminooxazoline 428 in 60% yield. The trans-bxomo-hydrin 428 was stirred in a suspension of potassium carbonate in methanol to form the epoxide 429 in 81% yield (Scheme 60).109... 

Uchida and co-workers have further exemplified their synthesis (cf. Vol.28, p.233) of cyclic isoureas, e.g. S a-carbatrehazolin 39, by condensing glycosyl isothiocyanates with the cyclitolamine trehazoline, and cyclizing the resulting thiourea adducts (with HgO) for further details see Chapter 19. cis-Fused 1,2-oxazolidine-2-thiones such as 40 were the exclusive products from reactions of 1,2-O-sulfinyl-a-D-gluco-furanose or -pyranose derivatives (i.e. 1,2-cyclic sulfites) with sodium thiocyanate. ... 

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