Carbohydrate nitrone cycloadditions

A. Bhattacharjee, S. Datta, P. Chattopadhyay, N. Ghoshal, A. P. Kundu, A. Pal, R. Mukhopadhyay, S. Chowdhury, A. Bhattacharjya, and A. Patra, Synthesis of chiral oxepanes and pyrans by 3-O-allyl-carbohydrate nitrone cycloaddition (3-OACNC), Tetrahedron, 59 (2003) 4623 -639. 

As shown in Scheme 2.21 Id, starting with N-allyl carbohydrate-nitrones (469), a series of chiral six- (470) and seven-membered(471) TV-heterocycles were synthesized (Scheme 2.227). A very interesting and useful aspect of this cycloaddition is the control of regioselectivity by the substitution at the nitrogen atom. Therefore, it is possible to direct reactions towards the syntheses of preferred six- or seven-membered heterocycles from carbohydrate derivatives (722). 

Intramolecular cycloaddition of fV-benzyl-substituted 3-O-allylhexose nitrones furnishes chiral oxepane derivatives. The regioselectivity of the cycloaddition depends on several factors such as (1) the structural nature of the nitrone, (2) substitution and stereochemistry at 3-C of the carbohydrate backbone, and (3) substitution at the terminus of the O-allyl moiety. A mixture of an oxepane and a pyran is formed in the intramolecular oxime olefin cycloaddition of a 3-O-allyl carbohydrate-derived oxime <2003T4623>. The highly stereoselective synthesis of oxepanes proceeds by intramolecular nitrone cycloaddition reactions on sugar-derived methallyl ethers <2003TA3899>. 

T. K. M. Shing, D. A. Elsley, and J. G. Gillhouley, A rapid entry to carbocycles from carbohydrates via intramolecular nitrone cycloaddition, J. Chem. Soc. Chem. Commun. (1989) 1280-1282. 

Enantioselective total synthesis of antifungal agent Sch-38516 is reported. Stereocontrolled carbohydrate synthesis is based on the 1,3-dipolar cycloaddition of chiral nitrone to vinylene carbonate, as shown in Eq. 8.53.79... 

The asymmetric tandem cycloaddition of the chiral carbohydrate nitroalkene (35) with ethyl vinyl ether involves the initial formation of the nitronate (36) which reacts exclusively with electron-withdrawing alkenes by 3 -I- 2-cycloaddition to yield chiral bicycles (37) and (38) (Scheme 12). ... 

Borrachero et al. (180) prepared a number of sugar isoxazolidines by the reaction of carbohydrate-functionalized nitrones with nitroalkenes (Scheme 1.33). They found a matched pair of chiral sugar cycloaddition reaction partners to be... 

I. Panfil, C. Belzecki, and M. Chmielewski, An entry to the optically pure p iactam skeleton based on 1,3-dipolar cycloaddition of nitrones to 4,6-di-0-acetyl-2,3-dideoxy-D-threo-hex-2-enonolactone, J. Carbohydr. Chem. 5 463 (1987). 

Osborn HMl, Gemmell N, Harwood LM (2002) 1,3-dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes. J Chem Soc Perkin Trans 1 2419-2438... 

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