2,3-Unsaturated glycosyl derivatives

The Ferrier reaction of glycal derivatives has been extensively studied and recently reviewed <2001TCC153>. Additionally, the transformation of glycals into 2,3-unsaturated glycosyl derivatives has also been reviewed... 

The transformation of glycals (1,2-unsaturated cyclic carbohydrate derivatives) into 2,3-unsaturated glycosyl derivatives, currently termed Ferrier rearrangement, is a well-established synthetic procedure with ample use in the fields of carbohydrate and organic chemistry. This article highlights the developments in the Ferrier rearrangement published in the literature since the last review, in 2013, to early 2016. 

The term glycal is used to define sugar derivatives having a double bond between C-1 and C-2. Accordingly, C-1 glycals are A1,2 unsaturated carbohydrate derivatives with a carbon substituent at the anomeric position. These compounds are versatile synthetic intermediates, owing to the variety of transformations associated with their enol ether functionality, and have found ample use in the preparation of C-glycosyl compounds,1 carbohydrate mimics,2 and natural products.3... 

Some of the most useful 2,3-unsaturated C-glycosyl derivatives are the allyl compounds such as 92, made by use of allyltrimethylsilane, and a notable feature of this compound is that it can be produced directly from tri-O-acetyl-D-glucal with DDQ as promoter.111 A further surprising feature of this C-allylation procedure, however, is its applicability to glycals that are not O-substituted. Reactions are carried out in dichloromethane-acetonitrile at low temperatures with trimethylsilyl triflate as catalyst, and almost quantitative yields of 2,3-unsaturated C-allyl glycosyl compounds are recorded, with the a anomers being formed almost exclusively.112... 

Some of this group are listed in Table 13.3 All the members are 3-alkenylphenols sometimes, as with campnospermanol, containing a keto function in the side chain. The highly unsaturated substance flexirubin is a phenolic ester from a bacterial source. Complex phenolic ether compounds, essentially 0-glycosyl derivatives of c6-(4-hydroxyphenyl)phthiocerol A have been isolated from mycobacterial sources (ref. 75). 

A crystal structural analysis of mwco-inositol is referred to in Chapter 21. iV-(2-chloroethyl)-iV-nitrosoureido derivatives of cyclopentane- and cyclohexane-tetrols are mentioned in Chapter 18. Unsaturated glycosylated cyclitol derivatives are referred to in Chapter 12. 

The n.m.r. data for 6-deoxy-6-fluoro-ot- and - D-glucopyranose obtained at 300 MHz in DjO has been reported with a discussion of chemical shifts and coupling constant values. N.m.r. data on the unsaturated sugar derivatives (5) and (6), as well as on some fructofuranose derivatives useful as intermediates in a new synthesis of sucrose, have been published. The complete elucidation of the H n.m.r. spectra of the 2,3-unsaturated glycosyl phosphonates of type (7)... 

Several more complex trisaccharides involving modified sugars have been prepared for example 1, which is an aureolic acid-related compound made from a 2-phenylthioglycosyl trichloroacetimidate derived from the glycal 2 by solid phase technology, and the C-3 trisaccharide 3 of antibiotic PI-080, the unsaturated unit of which was coupled using the relevant unsaturated glycosyl tetrazole derivative. ... 

Several 4-thio-D-glucofuranosylamine disaccharide derivatives such as 8 (a p, 1 3) were obtained by direct condensation of 4-thio-D-glucose with an amino-sugar. A review of the application of palladium si-allyl complexes of unsaturated carbohydrates in fuctionalization at the anomeric centre included the use of 7V-nucleophiles to provide unsaturated JV-glycosyl derivatives. Cyclic l,2-iV,0-phosphate derivatives of aldoses feature as intermediates in selective 2-0-phosphorylation reactions (see Chapter 7). 

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