Orthoester 286 Subject

Condensation products of 4(5//)-oxazolonium salts with aldehydes and orthoesters are the subject of a series of papers by Kosulina and co-workers Reaction of 2-methyl-4(5//)-oxazolonium perchlorates 44 with an ortho ester gives rise to an enol ether, which reacts with furanamides to afford the frani-eneamides 45 (Scheme 6.14). " Using electron deficient anilines in a three component condensation affords either 46 or 47 in 64-80% and 78-84% yields, respectively, depending on whether the reaction is performed in acetic acid or acetic anhydride. Electron-rich anilines are unreactive since they are merely protonated by the perchloric acid present in the reaction medium. ... 

Enol ether 13 is prepared from butanal 12 by acetalization with alcohol PMBOH 35. The resulting acetal 40 is subjected to elimination with phosphinic acid 36. Acetalization proceeds via nucleophilic attack of the alcohol on the protonated aldehyde 37, dehydratization of the hemiacetal 38 and further nucleophilic attack on the carbenium ion 39. Since all steps are reversible, the created water has to be removed to achieve quantitative turnover. This is carried out by the use of water binding agents or solvents (dry Na2S04, CaCl2, orthoesters) or azeotropic distillation. 

What if the prior art would motivate one of ordinary skill in the art to make the applicant s claimed invention but for a different reason than that relied on by the applicant Should it matter The following example, taken from a CAFC opinion decided this exact question.31 The named petitioner, Dillon, was an assignor of the invention to Union Oil Company, whose application for patent was rejected in the USPTO. After unsuccessfully appealing to the USPTO Board of Appeals, the petitioner appealed to the CAFC and the rejection of the patentability of the claims was affirmed. The subject matter of the relevant claims was directed to compositions containing /c/ra-orthoesters in hydrocarbon fuels and methods of reducing particulate emissions using those fefra-orthoesters in hydrocarbon fuel. To clarify the subject... 

The success of the Claisen-Cope rearrangement need not be limited to the production of aldehydes via enol ethers. Allylic alcohol (58) is successively transposed into a mixture of allylic isomers (59 Scheme 4), and is subjected to an orthoester Claisen rearrangement at 150 "C to provide ester (61). The moderate temperature of the Claisen step permits the isolation of an intermediate (c/. Scheme 3) prior to the final Cope rearrangement (195 C) to. y-unsaturated esters (60). The esters (60) are a 55 45 mixture of ( )- and (Z)-double bond isomers owing to the near equal steric bulk of the methyl and acetic acid residues in the transition state for the Cope rearrangement. ... 

The net result of all these competitive reactions is a possible mixture of normal and /3-glycosides and a possible mixture of two diastereo-isomeric orthoesters. In the course of the Konigs-Knorr procedure, water is usually formed from the reaction between hydrogen halide and silver oxide. The water formed, or deliberately employed, may take the part of the solvent alcohol, thus giving rise to products such as acidic orthoesters and normal tetra- and heptaacetates (for a disaccharide) of the sugars, and these compounds are subject to further changes, such as acyl migration. 

The final SnCl2-mediated glycosidation of the 2-phenylseleno glycosyl fluoride 267 and the alcohol 311 gave the oligosaccharide 312 with complete stereocontrol, which was subjected to Sinay s orthoester formation to afford everninomicin 13,384-1 (314) after successful deprotections, including reductive debenzylation and TBAF-induced desilylation. 

Reductions at anomeric positions, both by ionic and radical mechanisms, deliver hydrogen from the axial direction. Kahne prepared the hemithio orthoester 75 from thiolactone and subjected it to tin hydride reduction, which resulted in predonunant formation of the -glycoside [116] (O Scheme 40). 

Orthoester is the triether groups linked a carbon atom. Contrary to the ester that subject to acid-base catalyzed hydrolysis, orthoester is hydrolyzed faster under... 

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