Galactopyranose synthesis

Deoxy-3-[ F]fluoro-D-glucose ( F-3DFG) was prepared - 454,467,473-476 essentially according to the procedure for the cold synthesis (see Section 11,2), namely, treatment of248 with Cs F (in DMF or HMPA), tetraalkylammonium [ F]fluoride (DMF, HMPA, or MeCN) or K F (in acetamide). 6-Deoxy-6-[ F]fluoro-a-D-galactopyranose was likewise pre-pared aceording to the cold synthesis. ... 

In fact, other studies have shown that TMSOTf catalyzes the glycosylation of a silylated acceptor with a silylated hemiacetal donor [49]. Nudel man s procedure was applied to the synthesis [1-glucuronide 30, isolated in 57% yield. Kiyoi and Kondo have applied the TMSOTf activation protocol to protected L-fucose hemiacetal donors for glycopeptide synthesis and obtained glycopeptide fragment 31 in 74% yield (a p, 20 1) [50], Posner and Bull have developed a procedure that uses excess TMSOTf in the presence of molecular sieves (SYLOSIV A4) to synthesize various l.l -linked disaccharides such as the galactopyranose dimer 32 [51,52]. 

An alternative approach, in which the anomeric centre of the sugar is reacted with a carbon nucleophile, but the amino group is subsequently inserted at the other side or in both sides at the same time, is reported in Fig. 41 for the synthesis of a- and (3-homogalactonojirimycin.72 Reaction of 2,3,4,6-tetra-O-benzyl-p-D-galactopyranose with methylenetriphenylphosphorane generated an enitol on which the amino group was inserted as phtalimide by a double inversion process of the 5-OH, under Mitsunobu s conditions. 

The Arbuzov reaction has been applied for the synthesis of fluorinated carbohydrates. 1,2 3,4-Di-O-isopropylidene-a-D-galactopyran-ose 6-(N,N-diethyl-P-methylphosphonamidite) was treated with ethyl fluoroacetate, to afford 6-deoxy-6-fluoro-l,2 3,4-di-O-isopropylidene-a-D-galactopyranose in 19% yield.241 The corresponding 6-deoxy-6-fluoride was obtained in 60% yield by treatment of l,2 3,4-di-0-isopropylidene-a-D-galactopyranose 6-(dipropylphosphinite) with hexafluoropropene.242 The mechanism of this reaction has been discussed.243,244 In contrast, treatment of 1,2 -.3,4-di-O-isopropylidene-a-D-galactopyranose 6-(tetraethylphosphorodiamidite) with benzoyl fluoride yielded the corresponding 6-benzoate, not the 6-deoxy-6-flu-oride expected.245... 

A Synthesis of 3-0-(2-Acetamido-2-deoxy-a-D-galactopyranose and 3-O-of-D-galactopyranosyl-D-galactopyranose, R. U. Lemieux and R. V. Stick, Aust. J. Chem., 31 (1978) 901-905. 

A characteristic feature of the dianhydrohexopyranoses is their steric rigidity. Consequently, they usually react with high and predictable regio-and stereoselectivity, mainly by diaxial cleavage of the oxirane ring. Thus, they became versatile starting materials for synthesis of various carbohydrates as well as noncarbohydrate structures. The most important compounds are l,6 3,4-dianhydro-2-0-tosyl-/l-D-galactopyranose (146), the manno epoxide 143, the altro epoxide 159, and the 2,3- and 3,4-anhydro-a//o epoxides 138 and 139. The tosyl epoxide 146 (for its crystal structure,... 

P. A. Gent, R. Gigg, and A. A. E. Penglis, The allyl ether as a protecting group in carbohydrate chemistry. Part 9. Synthesis of derivatives of 1,6-anhydro-jS-D-galactopyranose, J. Chem. Soc., Perkin Trans. 1, (1976) 1395-1404. 

T. Ziegler and G. Herold, Preparation of diastereomeric 3,4-O-pyruvate acetal-containing D-galactopyranose derivatives, structural assignment and use for oligosaccharide synthesis, Liebigs Ann. Chem., (1994) 859-866. 

J. Jurczak, T. Bauer, and S. Jarosz, Stereospecific synthesis of 5,6-dihydro-2//-pyran system. High-pressure cycloaddition of l,2 3,4-di-0-isopropylidene a-D-galactopyranose-6-ulose to 1-methoxybuta-l,3-diene, Tetrahedron Lett., 25 (1984) 4809—4812. 

Zakharkin LI, Guseva VV, Sulaimankulova DD, Korneva GM (1988) Synthesis of 6-(z-2,7-octadienyI)-alpha-D-galactopyranoses. Zh Org Khim 24 119-121... 

The first synthesis of 2,3,4-trimethyl-D-galactose, which had previously been isolated from the hydrolysis products of methylated galac-tosans, was achieved by McCreath and F. Smith.20 1,6-Anhydro-D-galactopyranose, treated with dimethyl sulphate and alkali, underwent easy methylation and the resulting crystalline 2,3,4-trimethyl-l,6-anhydro-D-galactopyranose was conveniently hydrolyzed to the free sugar hydrate. 

An improved synthesis of prenyl-disphosphate-galactose involves conversion of the prenylphosphate (206) into the imidazolide by reaction with sulphinyldi-imidazole, and subsequent condensation with a-D-galactopyranose-l-phos-... 

Zhu, Y, Kong, F, Regio- and stereoselective synthesis of 1—>6 linked manno-, gluco-, and galactopyranose di-, tri-, and tetrasaccharides via orthoester intermediates, J. Carbohydr. Chem., 19, 837-848, 2000. 

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