Of 1,2-cyclopropanated sugars

N. V. Ganesh and N. Jayaraman, Synthesis of aryl, glycosyl, and azido septanosides through ring expansion of 1,2-cyclopropanated sugars, J. Org. Chem., 74 (2009) 739—746. 

Murali, R, Ramana, C V, Nagarajan, N, Synthesis of 1,2-cyclopropanated sugars from glycals, J. Chem. Soc. Chem. Common., 217—218, 1995. 

Beyer, J, Skaanderup, P R, Madsen, R, Platinum-catalyzed ring opening of 1,2-cyclopropanated sugars with 0-nucleophiles. Convenient synthesis of 2-C-branched carbohydrates, J. Am. Chem. Soc., 122, 9575-9583, 2000. 

C-Branched glycoside 6 was prepared by platinum-catalyzed ring opening of 1,2-cyclopropanated sugar 7 with the alcohol nucleophile 8 (Scheme 2.7) [9]. 

The ring opening of 1,2-cyclopropanated sugars not only is the way to expanded sugars, but can also provide the branched derivatives as proposed by Madsen [27] an example is shown in Figure 10.11. 

Treatment of 1,2-C-methylene carbohydrates, prepared by cyclopropanation of unsaturated sugars, with Lewis acids and trapping of the intermediate oxonium ion with a nucleophile is a convenient route to 2-substituted-2,3,6,7-tetrahydrooxepines <95TL683i>. Thus rearrangement of (55) with TMSOTf in acetonitrile in the presence of MeCN affords (56). The trapping nucleophile may be a substituent of the original carbohydrate, as demonstrated by the conversion of (57) into the bridged bicyclic oxepine (58). 

More recently, another methodology for sugar-fused butyrolactones employing glycal-derived cyclopropane precursors has been described by Chandrasekaran and co-workers (Scheme 44) [215]. In this case, hexofuranose- or hexopyranose-1,2-fused were cyclopropanated into compounds of type 181. After saponification with... 

Of the many substituted and functionalized alkenes that have been combined with diazo dipoles to give A -pyrazolines or products derived from them (i.e., A -pyrazolines, pyrazoles, cyclopropanes), only a selection will be mentioned. These include ot-alkylidene-cycloalkanones (62), -flavanones, -thioflavanones, -chroma-nones, and thiochromanones (63,64) a-arylidene-indanones and -indolones (65) diarylideneacetones (66) l-benzopyran-2(77)-ones (coumarins) (67,68) 4-nitro-1,2-oxazoles (69) 2-alkylidene-2-cyanoacetates (70) dimethyl 2,3-dicyanofuma-rate (71) tetracyanoethylene (72) tetraethyl ethylenetetracarboxylate (72) 1,4-quinones (35,73-75) 2-X-l,l,l-trifluoro-2-propene [X = Br, (76), SPh, SOPh, S02Ph (77)] nitroalkenes (78) including sugar nitroalkenes (79) 1-diethoxyphos-phoryl-1-alkenyl-sulfoxides (80) methyl 2-(acetylamino)cinnamate and -acrylate... 

Compound 110 (obtained by reaction of D-glucal with propargylic alcohol) was subjected to cyclization with Co2(CO)g, which led to a fused tricyclic derivative 111 (O Scheme 48) [97]. [2+2] Cycloaddition of carbenes to glycals is an efficient route leading to cyclopropanated sugars with high stereoselectivity [1]. Such cyclopropanes can be transformed into a number... 

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