Mannitol displacement reactions

In some related work, Foster and coworkers treated the di-O-iso-propylidene-D-mannitol di-p-toluenesulfonate (43) with sodium benzoate in W,W-dimethylformamide, and obtained, among a number of other products, the di-O-isopropylidene-D-iditol monobenzoate (46) and the di-O-isopropylidene-D-talitol dibenzoate (47). A rational sequence for these two products involves first, the Sn2 displacement on (43) to give the D-talitol compound (44), that yields the orthoester ion (45) by benzoyl-group participation. Conventional attack by water at C-1 leads to (46), whereas attack by benzoate ion at C-3 leads to (47). The authors suggested that participation reactions leading to (46) and (47) were... 

Displacements involving allylic systems. Allylic substitution reactions continue to receive considerable attention. Improvement by microwave is noted. " New ligands for the Pd-catalyzed reaction include iminophosphine 13, which is derived from 1-mesitylethylamine, pyridylphenylphosphine 14, and the phosphinite 15, obtained from D-glucosamine. Phospholanes such as 16, 17, 18, prepared from mannitol, are excellent ligands. 

The last phases of B. R. Baker s work that was completely devoted to carbohydrate chemistry were carried out between 1963 and 1966, when he was in residence at the State University of New York at Buffalo. He studied Sn2 displacements in comparison with neighboring-group displacements in the l,2 5,6-di-0-isopropylidene-n-mannitol and related systems, and showed that the competition between the two types of replacement reaction depends on the nucleophilic nature of the substituent group and the nature of the neighboring group and he used... 

Another study pertinent to the present discussion is that of the acid-catalyzed dehydration of tetratols, pentitols, and hexitols, all of which yield tetrahydrofuran derivatives as the primary products. These reactions are first order with respect to the alcohol and the acidity function Hq, and the direct relationship shown from plots of versus Hq implies that the reaction proceeds via a protonated intermediate.In all cases except one, the major cyclic product is derived from HO-5 displacement of water from C-1. The exception is D-mannitol (213), where HO-3 participation leads to a slight preference for formation of 2,5-anhydro-D-glucitol (214) over 1,4-anhydro-D-mannitol (215). Inversion at C-2 occurs with HO-5 participation during ring opening of the epoxide (214). 

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