116809-48-4

Upstream product

• 116809-47-3 Benzoic acid (2S,3R,4S,5R,6S)-2-iodomethyl-6-methoxy-4,5-bis-(toluene-4-sulfonyloxy)-tetrahydro-pyran-3-yl ester 
• 65556-00-5 methyl 4,6-di-O-benzylidene-2,3-di-O-tosyl-α-D-glucopyranoside 
• 101155-76-4 methyl 2,3-di-O-p-toluenesulfonyl-4-O-benzoyl-6-bromo-6-deoxy-α-D-glucopyranoside 

Downstream Products

• 101155-81-1 methyl 2-O-p-toluenesulfonyl-4,6-dideoxy-α-D-ribo-hexopyranoside 
• 116907-46-1 (3R,4R,6R)-6-Methyl-tetrahydro-pyran-2,3,4-triol 
• 116809-49-5 methyl 3,4-anhydro-6-deoxy-2-(tolylsulfonyl)allopyranoside 

Relevant academic research and scientific papers

Deoxygenation of carbohydrates by thiol-catalysed radical-chain redox rearrangement of the derived benzylidene acetals

Five- or six-membered cyclic benzylidene acetals, derived from 1,2- or 1,3-diol functionality in carbohydrates, undergo an efficient thiol-catalysed radical-chain redox rearrangement resulting in deoxygenation at one of the diol termini and formation of a benzoate ester function at the other. The role of the thiol is to act as a protic polarity-reversal catalyst to promote the overall abstraction of the acetal hydrogen atom by a nucleophilic alkyl radical. The redox rearrangement is carried out in refluxing octane and/or chlorobenzene as solvent at ca. 130°C and is initiated by thermal decomposition of di-tert-butyl peroxide (DTBP) or 2,2-bis(tert-butylperoxy)butane. The silanethiols (ButO)3SiSH and Pr3iSiSH (TIPST) are particularly efficient catalysts and the use of DTBP in conjunction with TIPST is generally the most effective and convenient combination. The reaction has been applied to the monodeoxygenation of a variety of monosaccharides by way of 1,2-, 3,4- and 4,6-O-benzylidene pyranoses and a 5,6-O-benzylidene furanose. It has also been applied to bring about the dideoxygenation of mannose and of the disaccharide α,α-trehalose. The use of p-methoxybenzylidene acetals offers no great advantage and ethylene acetals do not undergo significant redox rearrangement under similar conditions. Functional group compatibility is good and tosylate, epoxide and ketone functions do not interfere; it is not necessary to protect free OH groups. Because of the different mechanisms of the ring-opening step (homolytic versus heterolytic), the regioselectivity of the redox rearrangement can differ usefully from that resulting from the Hanessian-Hullar (H.-H.) and Collins reactions for brominative ring opening of benzylidene acetals. When simple deoxygenation of a carbohydrate is desired, the one-pot redox rearrangement offers an advantage over H.-H./Collins-based procedures in that the reductive debromination step (which often involves the use of toxic tin hydrides) required by the latter methodology is avoided.

Total Synthesis of (+)-Colletodiol: New Methodology for the Synthesis of Macrolactones

Synthetic efforts directed toward two different structures suggested for the macrocyclic bis(lactone) colletodiol are detailed.The initial approach to an incorrect structure (C11 epi) relies upon the manipulation of methyl α-D-glucopyranoside to set the required stereochemistry for the C8-C14 segment of the C11 epi structure.The second approach, initiated after structural revision based upon X-ray crystallographic evidence, employs a Lewis acid mediated addition of allylstannane 33 to β-alkoxy aldehyde 34 to set the stereochemistry of the C8-C14 subunit.This route, which employs a number of new synthetic reactions developed specifically for this problem, gives (+)-colletodiol in nine linear operations and 8.2percent overall yield.