Diacetone mannose

These same authors also prepared the xanthates from diacetone mannose and diacetone galactose, but in no case were they able to effect the unsaturation of the xanthate according to the method of Chugaev. This was the original purpose of the investigation they had hoped for a better preparation of unsaturated compounds, as, for example ... 

Synthesis from o-mannose Syntheses of a-homonojirimycin (1), 6-cp/-a-homo-mannojirimycin (39) and the pipecolic acid derivative 36 from D-mannose have been reported (Scheme 5). The azidolactone 31, ° prepared from diacetone mannose (30), nnderwent selective removal of the terminal isopropylidene gronp, followed by selective protection of the resnlting primary hydroxyl gronp with fcrt-butyldimethylsilyl chloride to... 

The conversion of the amide group in 34 into the carboxy group via 35 seems to be a promising way to solve the "cunide problem" of B-lactam syntheses by 4CC (refs. 2,21). The conversion of B-lactam amides into the carboxylic acids via the esters was very successful in the hands of Hofheinz and Isenring (ref. 22) who worked with the N-benzhydryl amides of nocardicin derivatives. The stereoselective and regiose-lective 1,3-dipolar cycloaddition of chiral nitrones to benzyl crotonate is a key step in our approach to thienamy-cine (ref. 23) and related carbapenam derivatives. Besides chiral 2-phenylethyl hydroxylamine (ref. 24) the 1-hydro-xylamino derivative of 2,3-5,6-diacetone mannose (ref. 25) is a promising source of chiral nitrones for such enantiose-lective cycloadditions. 

The first asymetric synthesis of (+)-biotin (Scheme 30) was reported by Ohrui and Emoto 68). The starting material was diacetone mannose (2,3 5,6-di-O-isopropylidene mannofuranose), (116). Although... 

L-Mannitol does not occur naturally but is obtained by the reduction of L-mannose or L-mannonic acid lactone (80). It can be synthesized from the relatively abundant L-arabinose through the L-mannose and L-glucose cyanohydrins, conversion to the phenylhydrazines which are separated, liberation of L-mannose, and reduction with sodium borohydride (81). Another synthesis is from L-inositol (obtained from its monomethyl ether, quebrachitol) through the diacetonate, periodate oxidation to the blocked dialdehyde, reduction, and removal of the acetone blocking groups (82). 

In more complex examples, diacetone derivatives of glucose, of mannose, galactose and glucoheptonolactone have played a vital role for the specific synthesis of polyhydroxylatedpiperidines a group... 

Diacetone glucose" "Diacetone galactose" "Dicyclohexylidene mannose"... 

The aldehyde 73 was prepared from diacetone D-mannose 72 in 80% overall yield (Scheme 9) Treatment of 73 with allyltrimethylsilane followed by benzylation gave the benzyl ether 74. Opening of the furanoside ring gave the hydroxyalkene 75 (78%), which underwent hydroboration followed by oxidation of the resulting diol to afford the ketoaldehyde 76. Removal of the p-methoxybenzyl group with DDQ provided 77, which... 

The course of diacetonation of glucose, galactose and mannose (Schemes 2, 19 and 30 respectively) form an interesting contrast. Mills has presented a rationalization for... 

Conversion of 2,3,4,6-tetra-C -benzyl-D-mannose to the corresponding dimethyl phosphinothioates gave a useful a-mannosylating agent. Condensation is effected with silver perchlorate and the yield of disaccharide given with diacetone-D-galactose was 80%. ... 

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