Mannitol 6-tosylate

An interesting feature of the synthesis is the use of allyl as a two-carbon extension unit. This has been used in the stereospecific synthesis of dicyclohexano-18-crown-6 (see Eq. 3.13) and by Cram for formation of an aldehyde unit (see Eq. 3.55). In the present case, mannitol bis-acetonide was converted into its allyl ether which was ozonized (reductive workup) to afford the bis-ethyleneoxy derivative. The latter two groups were tosylated and the derivative was allowed to react with its precursor to afford the chiral crown. The entire process is shown below in Eq. (3.59). 

Glacial acetic acid plus concentrated hydrochloric acid was used196 for deacetonation of a di-O-benzoyl- mono-O-isopropylidene-di-O-tosyl-D-mannitol (during 5 hours at 15-20°), and for hydrolysis236 of the diethyl acetal of 2,3-di-0-tosyl-D,L-glycerose by treatment during one hour at 100-105°. 

Sulfonic esters of sugar alcohols often react similarly with ammonia thus, l,4 3,6-dianhydro-2,5-di-0-tosyl-D-mannitol and -sorbitol give326 the corresponding 2,5-diamino-2,5-dideoxy derivatives. However, 1,4 3,6-dianhydro-L-iditol affords326 a compound thought to be 1,4 3,6-dianhydro-2,5-dideoxy-2,5-imino-D-mannitol. 

Lithium chloride, preferably dissolved in absolute ethanol, has also been used306 419 420 for preparing alkyl chlorides. Dissolved in absolute ethanol-acetone (1 1, by vol.), it has recently414 found application with alditol sulfonates. Its action on l,4 3,6-dianhydro-2,5-di-0-mesyl-L-iditol, l,4 3,6-dianhydro-2,5-di-0-mesyl-D-mannitol, and l,4 3,6-dian-hydro-2,5-di-0-mesyl- (and -2,5-di-O-tosyl-) sorbitol resembles the action of sodium iodide on these compounds, i.e., the first displays no appreciable reaction, the second gives the 2,5-dichloro-2,5-dideoxy derivative, and the last two afford the respective monochloromonodeoxy-mono-O-sulfonyl derivatives. Treatment of l,4 3,6-dianhydro-2,5-di-0-mesyl-sorbitol during 48 hours at 180-90° gives some of a dianhydro-mono-chloromonodeoxy-sorbitoleen. 

The behavior towards potassium thiolacetate of a few alditols bearing acetal rings has been studied. On refluxing in acetone for 6 hours, 2,3,4,5-di-0-methylene-l,6-di-0-tosyl-D-mannitol gave36 an 89% yield of the... 

The extension of the reaction with sodium iodide to tosyl derivatives of other acetals of iditol, glucitol, and mannitol could provide evidence for the conformation of 2,4 3,5-diacetals of mannitol and, more important, lead to a clarification of the steric requirements of this reaction. The importance of 2,4 3,5-diacetals of talitol, at present unknown, is now clear they will have one axial and one equatorial terminal group (see LIU), and the trans ring junction imposes a rigidity of conformation greater than that of any of the diacetals with cis junctions. 

Rules (1) and (3) are extensions of the arguments used by Matheson and Angyal " to explain the behavior of the di-O-tosyl derivatives of the three dianhydrides toward sodium iodide. These authors found that, in the d-mannitol derivative, both tosyloxy groups are readily replaceable by iodine but in the D-glucitol derivative only one, and in the L-iditol derivative neither, tosyloxy group was replaceable. Wiggins and Wood had obtained a parallel series of results from reactions of the di-O-tosyl and di-O-mesyl... 

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