5,6-unsaturated hexopyranose derivatives

This process (also known as the Ferrier II Reaction ) has proved to be of considerable value for the efficient, one-step conversion of 5,6-unsaturated hexopyranose derivatives into functionalized cyclohexanones useful for the preparation of such enantiomerically pure compounds as inositols and their amino, deoxy, unsaturated and selectively O-substituted derivatives, notably phosphate esters. In addition, the products of the carbocyclization have been incorporated into many complex compounds of interest in biological and medicinal chemistry. ... 

Compounds of this class, for example, hexopyranose derivatives having the general formula (123) (see Table II), have most frequently been prepared from the corresponding 6-deoxy-6-iodo or 6-bromo-6-deoxy derivatives of suitably protected aldohexoses or aldohexosides by allowing them to react at room temperature with silver fluoride in pyridine. Alternatively, for example, the 5,6-unsaturated derivative of 1,2 3,4-di-O-iso-propylidene-a-D-galaotopyranose was prepared from the 6-deoxy-6-iodo compound by heating at 130° with sodium methoxide in methanol. Properties of some members of this class are given in Table II. 

A convenient approach for the preparation of 3-deoxy-D-xy/o-hexopyranose (27) starts from 1,2 5,6-di-(9-isopropylidene-ot-D-glucofuranose and proceeds via the 3,4-unsaturated derivative 28 (Scheme 15).80... 

J. PeckaandM. Cerny, Syntheses with anhydro sugars. 15. Syntheses of l,6-anhydro-2,3,4-trideoxy-jS-D-glycero-hexopyranose and its unsaturated derivatives as model substances for studying the optical rotation of sugars, Collect. Czech. Chem. Commun., 38 (1973) 132-142. 

Chiara et al. also reported the type [C] reaction, the cyciization between carbonyl compounds and oximes [220,221]. As illustrated in O Fig. 17, three types of substrate were s)uithesized from hexopyranoses and pentopyranoses, and the terminal O-benzylformaldoxime-ketones and the terminal O-benzylformaldoxime-a, /3-unsaturated esters were synthesized from a series of hexopyranoses, and meanwhile the terminal O-benzylformaldoxime-aldehydes were derived from a series of pentopyranoses (O Fig. 17). 

A number of -acyl- and thioureido-derivatives of 3 -amino-3 -deoxythymidine have been prepared. 1 0 Michael addition of phthalimide to enal (81) was used in the synthesis of the 3 -amino-2 ,3 -dideoxyhexo-furanose nucleosides (82) (all four isomers, R=H, Me, halogen),191 and a similar enal prepared by mercuric-ion catalysed hydrolysis of L-rhamnal was used in the same way to make the L-acosaminyl nucleoside (83) and its -anomer, and the L-ristosaminyl systems (epimers at C-3 ). 2 Michael addition of 1,2,4-triazole to (81) led, after base-sugar condensation, to the triazolyl-substituted nucleosides (84, B=T, U), together with the analogous hexopyranose systems. 93 xhe imidazolyl nucleosides (85) can be made by reaction of 3 -amino-3 -deoxythymidine with l,4-dinitroimidazoles, 9 whilst the unsaturated imidazole nucleoside (87) was made by treating the phenylselenone (86) (see Section 6) with imidazole. 195... 

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