Oxazolidine, sugar derivatives

The traditional method for preparing oxazolidines is to heat a mixture of amino alcohol and aldehyde in a solvent such as benzene with removal of water. A milder procedure that affords some products in high yield when they would otherwise be obtained in only trace amounts is to dehydrate the same mixture with molecular sieves in methylene chloride at room temperature <89JHC1687>. A method that has been effective with amino sugar derivatives is to cyclize with dibromomethane under phase transfer conditions <93Mi 304-02>. 

Uzan and co-workers311 have reported an alternative route for the preparation of pyranose and furanose c/.v-l,2-fused oxazolidine-2-thiones that uses 1,2-O-sulfinyl sugar derivatives (169) as precursors. After treatment with sodium thiocyanate in DMF at 80°C, the bicyclic thiocarbamales (172) were isolated in 60-90% yield. The proposed mechanism involves formation of a -configured thiocyanate (170) that isomerizes to the a-isothiocyanate derivative (171) under the reaction conditions (Scheme 49). 

Fused ring heterocycles, prepared by cyclization of substrates with a tethered nitrogen nucleophile, have been used in the synthesis of amino sugars and aminocyclitols. The examples shown in Table 28 make use of imidate-type functionality (equation 101) to insure nucleophilic attack by nitrogen. The bro-mocyclization of N,W-dialkylaminomethyl ethers of 2-cyclohexen-l-ol to form bicyclic oxazolidine derivatives has been reported also.228b... 

Treatment of 5-deoxy-5-halogeno nucleosides of adenine and uracil with trimethylamine yielded the corresponding 5-deoxy-5-trimethylammonium salts, whose interaction with anionic polynucleotides was then examined. Various A -alkyl, A -cycloalkyl, and iV-alkaryl derivatives of 3-amino-3-deoxy-and 3, 5 -diamino-3, 5 -dideoxy-adenosine have been prepared from the amino-sugar nucleosides the 3 -benzylamino derivative gave the unusual oxazolidine derivative (52). ° ... 

The electron impact mass spectra of 29 oxazolidines derived from sugars, such as 71, have been recorded. Potentiometry has been used to study the acid-base and metal ion complexing properties of 2-benzylamino-2-deoxy-D-g/ycero-D-to/o-heptonic acid in aqueous solution. Complexation was similar to that seen with alanine and the D-g/ycero-D-g /o-analogue, with bodi... 

A new method for synthesis of W-alkyl- and N,iV-dialkyl-derivatives of 2-amino-2-deoxy-D-glucose is shown in Scheme 19. Oxazolidine derivatives such as 61 related to muramic acids, but with conformational restrictions, wrae synthesized by alkylation of the corresponding 2-acylamino-2-deoxy-3-hydroxy-sugars with dichloroacetic acid. ... 

Methylthiazolidine-4-carboxylic acid, a condensation product of cysteine and acetaldehyde, occurs even in human blood as a consequence of ethanol consumption. Serine and threonine analogously produce C-2 substituted (2J S,4S)-oxazolidine-4-carboxylic acids (2-124). Heterocyclic products, C-2 substituted (2J S,4S)-pyrimidine-4-carboxylic acids, are also produced in the reaction of aldehydes with asparagine (2-125). Phenylalanine yields C-1 substituted (lJ S,3S)-tetrahydroisoquinoline-3-carboxylic acids (2-126) and analogous products arise from tyrosine. Tryptophan reacts with aldehydes under the formation of 9H-pyrido[3,4-b]indole (also known as -carboline or norharmane) derivatives, (lJ S,3S)-l,2,3,4-tetrahydro-fi-carboline-3-carboxylic acids (2-127, R = H or alkyl or residues of other aldehydes and sugars), the reaction of tryptamine yields the corresponding (lRS)-l,2,3,4-tetrahydro-P-carbolines. 

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