Carbocycles from sugar

Other methods that rely on the use of the carbohydrate template to construct fused carbocycles have been successfully investigated as strategies for the formation of carbocycles from sugars. Chirality transfer from the sugar to the new carbocycle is observed for these reactions. These annulation reactions are the subject of the second part of this section. 

K. Krohn, S. Grignard, and G. BSmer, From sugars to carbocycles. 4. Exclusive seven-membered ring formation from D-glucose, Tetrahedron Asymmetry 5 2485 (1994). 

A. Carbocycles from unsaturated halo sugars by hex-5-enyl... 

A. Carbocycles from Unsaturated Halo Sugars by Hex-5-enyl Radical Cyclizatlon [8]... 

C. S. Wilcox and L. M. Thomasco, New syntheses of carbocycles from carbohydrates. Cycliza-tion of radicals derived from unsaturated halo sugars, J. Org. Chem. 50 546 (1985) see also S. Hanessian, D. S. Dhanoa, and P, L. Beaulieu, Synthesis of tt-substituted a,P-unsaturated esters via radical-induced cyclizations, Can. J. Chem. 65 1859 (1987). 

Cycloaddition to a-P-unsaturated carbonyl systems represented by different carbohydrate enones yield annulated osides. These bicyclic molecules are used for synthesis of carbocyclic systems using the stereochemical information issued from sugar... 

Horton, D, Koh, D, Generahzed approach from sugars to enantiomerically pure tetra-C-substituted carbocycles. Tetrahedron Lett., 34, 2283-2286, 1993. 

Variants of this reaction used to construct inositols were introduced by Prestwich [301] and Sinay [302]. These new methods have been reviewed elsewhere [303]. Additionally, a chapter of this book deals with methods of carbocyclization to form carbasugars from sugars. 

Fraser-Reid, B, Tsang, R, Carbocycles from carbohydrates the annulated sugar approach. In Strategies and Tactics in Organic Synthesis, Vol. 2, Lindberg, T, Ed., Academic Press, New York,... 

Wilcox CS, Tomasco LM (1985) New syntheses of carbocycles from carbohydrates. Cyclization of radicals derived from unsaturated halo sugars. J Org Chem 50 546-547... 

Cycloadditions to these enones yield annulated pyranosides , a number of which have become available in recent years in the authors laboratory (23). These bicyclic molecules open avenues for transcription of stereochemical information from sugars to carbocyclic systems, generalized procedures for which are currently not available. 

The reaction has broad potential in synthesis of enantiomerically pure, polysubstituted carbocycles by chirality transfer from sugar precursors ... 

The widespread occurrence and biological significance of polyoxygenated carbocycles provided the impetus to apply RCM to sugar-derived dienes. Carbohydrate carbocyclization based on a sequence of Vasella reductive opening of iodo-substituted methyl glycosides [25], and RCM of the dienes available from the resulting unsaturated aldehydes, were used to prepare a series of natural compounds (Schemes 5-7). 

The same group proposed also a general route to carbocycles of type 49.31 Starting from D-glucose, the precursor 46 was prepared in a few standard steps it could be used either for the synthesis of imino sugars or carbocycles... 

Scheme 2 Carbocyclic compounds from furanose sugars.

T. V. RajanBabu, From carbohydrates to optically active carbocycles, 1 Stereochemical control in sugar hex-5-enyl radical cyclization, J. Am. Chem. Soc. 109 609 (1987). 

---