Mannitol 2,5-0-methylene

C26H2608 2,4 3,5-Di-O-methylene-D-mannitol 1,6-di-trans-cinnamate (OMMTCI)115... 

C7Hu06 Na+ Cl 2,5-O-Methylene-D-mannitol sodium chloride MMANSC 37 379... 

CisH22O10 l,3,4,6-Tetra-0-acetyl-2,5-0-methylene-D-mannitol AMMANN 38 462... 

Closely related to the synthetic work reported in the previous section is the incorporation (131) of a 2,5-anhydro-3,4Hdi-0-methyl-D-mannitol residue (Figure 15) into the 18-crown-6 derivative d-91. Other derivatives of D-mannitol that have been built into crown ether receptors include l,4 3,6-dianhydro-D-maiuiitol (132), l,3 4,6-di-0-methylene-D-marmitol (13 134), and 1,3 4,6-di-O-benzylidene-D-mannitol (134). Examples of chiral crown compounds containing these residues include dd-92, dd-93, d-94, and d-95. Although not derived from carbohydrates—but rather (135) from the terpene, (-t-)-pulegone—... 

The way of designing aixi synthesizing a chiral 20-crown-6 derivative ddd-98 incorporating two 1,2-U-isopropylidene-D-mannitol residues and one 1,3 4,6-di-O-methylene-D-mannitol residue starting from appropriately constracted mono- and di-extended diacetone mannitol units is outlined (136) in Scheme 6. It relies on the local C2 symmetry of all the carbr ydrate residues and the C2 symmetry present in the final product. By developing a strategy not dissimilar to that described in Scheme 3, dithiol-bearing chiral 18-crown-6 derivatives... 

J. F. Stoddart and W. A. Szarek, Conformational studies on 1,3-dioxepans. Part III. 2,5-0-methylene-D-mannitol and some related compounds, J. Chem. Soc. B (1971) 437 442. 

As the acetal group in 2,5-O-methylene-D-mannitol is relatively resistant to hydrolysis, S. B. Baker" studied the stabilities of 1,4 3,6-dianhydro-2,5-0-methylene-D-mannitol and -D-iditol relative to that of the D-mannitol acetal. He synthesized l,4 3,6-dianhydro-2,5-0-methylene-D-mannitol by cyclizing 2,5-0-methylene-l,6-di-0-p-tolyl-sulfonyl-D-mannitol or by methylenation of l,4 3,6-dianhydro-D-man-nitol. The D-iditol isomer was prepared by cyclizing 1,6-di-O-benzoyl-... 

O-Methylene-D-mannitol is quite stable to hydrolysis by dilute... 

A 1 1 aquo complex was prepared with the chiral crown 1,3 1, 3 4,6 4, 6 -tetra-0-methylene-2,2 5,5 -bis-0-oxydiethylene-di-D-mannitol (9). In the crystal the host molecule has C2 symmetry, and the hydrogen bonded water guest molecule lies on the twofold axis. The oxygen atom of the water sits above the crown and is hydrogen bonded (H -O = 1.96 A) to two ether linkages adjacent to the six-membered rings. 

The dependence of the acid-lability of trialkylsilyl and related ethers on the type of substitution at silicon is illustrated by the formation302 of l-0-(tert-butyldiphenylsilyl)-2,3 4,5-di-0-methylene-D-mannitol (47) in 96% yield on treatment of 6-0-(terf-butyldimethylsilyl)-l-0-(fert-butyldiphenylsilyl)-2,3 4,5-di-O-methylene-D-manni-tol (48) with 80% acetic acid. 

Action of tf-Bromosncdnimide In Dimethytsulfoxide. An alternative to die classic methylenation of diols has been offered by the simple procedure using W-bromosuc-cinimide in dimethylsulfoxide and has been applied, for instance, to the acetalation of D-mannitol and D-ribofuranosides [90],... 

LXIX 1,6-Diamino-1,6-dideoxy-2,4 3,5-di-0-methylen-mannitol CeH1604N2 204,2 m-Kre- sol 1,2 589 +93 ... 

C7HMOe NaCl 2,5-O-Methylene-L-mannitol-sodium chloride19... 

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 readily available [77, 78] l,6-di-0-benzoyl-3,4-0-benzylidene-2,5-0-methy-lene-D-mannitol has been converted [79] into the benzyl ether (60), which on periodate oxidation and borohydride reduction gives the methylene acetal (61) which readily gives 1 -O-benzyl-L-glycerol for use in lipid synthesis. The acyl derivative (62) has been used [80] in glycolipid synthesis by glycosidation of the hydroxyl group. 

When the methylenation of D-mannitol is carried out at a higher temperature and for a shorter time, there is produced a dimethylene-D-mannitol (m. p. 204-208°), in addition to the triacetal previously mentioned.68 The dimethylene compound is not oxidized by periodic acid and its ditosyl ester does not exchange with sodium iodide, even in acetic anhydride at 140°.62 Consequently it must be either 1,2,4,6- or 1,3,4,6-dimethylene-D-mannitol (the 1,2,4,6- and 1,3,5,6-structures are identical) the 1,3 4,6-structure was favored by Ness, Hann and Hudson40 in view of the rapidity of its conversion into 1,3 2,5 4,6-trimethylene-D-mannitol. 

An isomeric dimethylene-D-mannitol (m. p. 139°) was isolated by Haskins, Hann and Hudson62 following the methylenation and saponification of 1,6-dibenzoyl-D-mannitol. Haworth and Wiggins62 found later that a 1,6-dibenzoyl-monomethylene-D-mannitol, which was not the... 

They found that these rules complied with the structures that were then known for the methylene acetals of sorbitol, mannitol, dulcitol, iditol, 6-desoxy-sorbitol, xylitol and ribitol. From the rules they predicted structures for methylene acetals of allitol and talitol, and several of these predicted acetals have been discovered in later researches. Among the... 

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