Synthesis from D-fructose

The respective D-piscopyranose derivative 52 was prepared from 32 by acid hydrolysis of the acetonide moiety to give 48, followed by complete benzylation to provide 49. Then 

Removal of the protecting groups from the key intermediates 47 and 52 furnished the same equilibrium mixture of the furanose and pyranose derivatives 53 and 54. These observations can be explained to be due to the tautomerism that has taken place through the open chain intermediate 55. Thermal treatment of this equilibrium mixture afforded 56, which was converted to 1 and 2 in a 1 1.3 ratio and 90% yield. 

5-tri-0-benzoyl-(3-D-ribofuranosyl cyanide (57) was converted with manganese(lV) oxide in dichloromethane to the amide 58 in 95% yield, which upon free radical bromi-nation with NBS and benzoyl peroxide produced the a-bromo amide 59 stereoselectively. Spirocyclization of 59 was effected with freshly prepared silver cyanate at 80°C in anhy-drons nitromethane to furnish a 1 2 mixture of 60 and 61 in 46% yield. The minor isomer 60 could be converted to the major one 61 with camphorsulfonic acid. Deprotection of 61 with LiOOH led to 1 in 90% yield. 

67 and 68 with TPAP in the presence of morpholine-A-oxide gave a single product 70 in 63% yield via the intermediate imine 69. 

The amine 70 was treated with potassinm cyanate in acetic acid to yield 71 (76%). Cyclization of 71 by treatment with potassinm fcr(-bntoxide in DMF afforded the cyclo-hexylidene cp/-hydantocidin 73 via 72 in 61% yield from 70. Acetylation of 73 gave 74, 

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I. Izquierdo Cubero, M. T. P. Lopez Espinosa, and A. C. Richardson, Enantiospecific synthesis from D-fructose of (2S,5R) and (2R,5R)-2-methyl-l,6-dioxaspiro[4.5]decane [The odour bouquet, minor components, of Paravespula vulgaris (L.)],./. Chem. Ecol., 19 (1993) 1265-1283. 

Banfi, L, Beretta, M G, Colombo, L, Gennari, C, Scolastico, C, 2-Benzoylamino-2-deoxy-2-hydrox3miethyl-D-hexono-1,4-lactones synthesis from D-fructose and utilization in the total s3mthesis of thermoz3miocidin (myriocin), J. Chem. Soc., Perkin. Trans. 1, 1613-1619, 1983. 

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