Ethers, cyclic, cleavage reagents

We investigated an interaction of 2-acyl( clohexane-l,3-diones la-c containing a perfluoroalkylated side chain with o-phenylenediamine. A direct reaction of the latter with o-phenylenediamine produees a mixture of acid cleavage products, as reported for their aeyelie analogues [7], As an alternative approach to the synthesis of perfluoroalkylated dibenzo[b,e][l,4]diazepinones, an interaction of enol ethers of 2-perfluoroalkanoylcyclohexane-l,3-diones la- c with o-phenylenediamine is proposed, beeause of an advanced reactivity of enol ethers to nucleophilic reagents versus the initial cyclic P,P -triketones [8],... 

Because of the special structural requirements of the resin-bound substrate, this type of cleavage reaction lacks general applicability. Some of the few examples that have been reported are listed in Table 3.19. Lactones have also been obtained by acid-catalyzed lactonization of resin-bound 4-hydroxy or 3-oxiranyl carboxylic acids [399]. Treatment of polystyrene-bound cyclic acetals with Jones reagent also leads to the release of lactones into solution (Entry 5, Table 3.19). Resin-bound benzylic aryl or alkyl carbonates have been converted into esters by treatment with acyl halides and Lewis acids (Entry 6, Table 3.19). Similarly, alcohols bound to insoluble supports as benzyl ethers can be cleaved from the support and simultaneously converted into esters by treatment with acyl halides [400]. Esters have also been prepared by treatment of carboxylic acids with an excess of polystyrene-bound triazenes here, diazo-nium salts are released into solution, which serve to O-alkylate the acid (Entry 7, Table 3.19). This strategy can also be used to prepare sulfonates [401]. 

In the first step the cyclic acetal is subjected to acid cleavage, after which all the free alcohol functions are protected as TBS ethers with the aid of the very reactive silylation reagent I BS triflate. The primary alcohol is then deprotected under mild conditions and oxi-di/ed with FDC to a carboxylic acid. 

The boron reagent 1 is recommended also for cleavage of mono MEM or methoxymethyl ethers of 1,2- or 1,3-diols, which are cleaved by acids mainly to cyclic diol foimals. 

Brown reported that the reagent used for the reductive cleavage of cyclic ethers, a lithium triethylborohydride-aluminum fert-butoxide complex (from lithium... 

Although widely used as a dehydration reagent, Martin s sulfurane is also known to facilitate amide cleavage reactions,7 cyclic ether (including epoxide) formations,8 and sulfilimine syntheses.9 In the 1970s Martin demonstrated all of these transformations in his series of papers outlining the reactivity of the title sulfurane. 

Without additional reagents Cleavage of ethers by sulfonates Acoxysulfonates from cyclic ethers... 

Introduction. (l/ ,5i -2//-l,5-Benzodithiepin-3(4/ -one 1,5-dioxide (C2-symmetric his-sulfoxide 1) has been used as a chiral auxiliary for asymmetric desymmetrization of cyclic meso-1,2-diols via diastereoselective acetal cleavage reaction. The procedure consists of three steps (eq 1), that is, acetalization (step 1), acetal cleavage reaction followed by benzylation (step 2), and hydrolysis of the vinyl ether (step 3). Due to the Ca-symmetry of 1, the chiral auxiliary gives only one product in step 1. In addition, no regio- or geometric isomers of the enol ether are formed in step 2. This reagent can be recovered by acid-promoted hydrolysis and reused. 

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