Formolysis

The relative rates of reaction for several different allylic systems are presented in Table 1. The data obtained by Vernon59 on the formolysis of allyl chlorides have been used as a standard for ionization. 

Formation of rearranged products in the solvolysis of homopropargyl systems need not involve triple-bond participation and vinyl cations in all instances. Ward and Sherman investigated the formolysis of 4-phenyl-1-butyn-l-yl brosylate, 57 (80). At 80°C in the presence of one equivalent of pyridine, they observed formation of phenyl cyclopropyl ketone, 58, and... 

Triple-bond participation was also observed in the formolysis of 64 (81). Tosylate 64 in formic acid at 60° in the presence of sodium formate gave a nearly quantitative yield of 5-methyl-4-hexen-3-one, 65. 

In a study completed during the early development of f.a.b.-m.s., both f.d. and f.a.b. were used to characterize 101 fractions containing neutral oligosaccharides isolated from human milk. Samples were examined as their peracetylated alditols. In subsequent work, the structures of two minor acidic oligosaccharides from human milk were investigated. The per-methylated derivatives were analyzed by f.a.b.-m.s., and their compositions and sequences were defined by the f.a.b. data. Methylation analysis and partial formolysis were the other principal methods used. 

Cram and Singer also noted a remarkable difference in the solvolysis of the systems 100b and 101 b. On acetolysis of the a-C deuterated model compound 101c the deuterium was found to be scrambled with 46% D recovered in the position (on hydrolysis 26% D was recovered the / position), whereas in the acetolysis and formolysis of 100c the deuterium remained totally undisturbed in the a position. 

Recent studies on the solvolysis of the diastereomeric tosylates 107 support this hypothesis. The acetolysis and formolysis of these compounds proceed with high retention of configuration 90> while in ordinary simple acetolysis of tosyl esters of secondary alcohols containing no neighboring groups, inversion predominates. 

Glycosidic linkages may also be cleaved in other solvents, such as methanol. In this case, water is rigorously excluded, so that the elements of a molecule of methanol are added across the glycosidic linkage to afford the methyl glycosides. Methanolysis is usually catalyzed by the addition of dry hydrogen chloride to the methanol. Other solvents, such as acetic anhydride-acetic acid (acetolysis) and formic acid (formolysis), are occasionally used for special purposes. 

Formolysis and acetolysis are not common methods for cleavage of glycosidic linkages. They do have some unique applications, however. For instance, methylated polysaccharides are not generally soluble in hot water, and consequently, hydrolysis is best preceded by formolysis under these circumstances. For example, 5 mg of methylated polysaccharide is dissolved in 3 mL of 90% formic acid, and the solution is kept for 2 h at 100°. The formic acid is removed by evaporation at 40°. The residue is dissolved in 1 mL of 250 mM sulfuric acid and the solution is heated for 12 h at 100°, cooled, the acid neutralized with barium carbonate, the... 

Buffered acetolysis of tosylate 420 gives diene 421 as the major product along with unrearranged acetate. In buffered formolysis, the cis formate 422 evolves as the principal component. The structural assignments were confirmed by the chemical intercorrelations shown... 

The problems inherent in the hydrolysis of methylated polysaccharides are similar to those outlined, but, in addition, the possibility of occurrence of demethylation must be considered. This matter has been studied by Croon and coworkers,102 who found that hydrogen chloride, either in water or methanol, causes a significant amount of demethylation. Formolysis in 98% formic acid caused considerable degradation, whereas 90% formic acid or sulfuric acid gave acceptable results. The hydrolysis of a methylated dextran with 90% formic acid has been described in detail.103 The methanolysis of a methylated... 

Even more scrambling was found in trifluoroacetolysis of l-propyl-l-14C-mercuric perchlorate.25 However, protonated cyclopropane intermediates accounted for less than 1% of the products from diazotization of labeled isobutylamine26 and from formolysis of labeled 1-propyl tosylate.27... 

Various techniques have been utilized for sequencing the glycosyl residues of polysaccharides and oligosaccharides. These techniques are elaborations of the commonplace procedure of converting polysaccharides, by partial hydrolysis, into structurally analyzable oligosaccharides. This conversion is generally achieved by partial hydrolysis with acid, by acetolysis,131 or by formolysis.62 These reagents may differ in the... 

Treatment of cm- and fraws-cycloundeoene and cyclododecene with perform acid likewise gives complex mixtures of products derivable by 1 abnormal formolysis of the corresponding epoxides.1401-14o By contrast, mothylenecyclooctane oxide yields no diole on treatment with formic acid and subsequent alkaline hydrolysis, the main product being formykycJooctame.1 2 ... 

Chuchani and coworkers160 examined the participation by a more remote benzene ring in co-phenylalkyl chlorides. Analysis of the data of Table 16 indicated that participation of C6H5 at the 2-, 4- and 5-positions is more favored than in the 3-position which seems unimportant. The relative sequence found in this work is somewhat similar to that found in the formolysis and acetolysis of co-phenylalkyl / -bromobenzenesulfonates by Heck and Winstein161 ... 

Formolysis of (264) produces the formate ester of (259) and (265) in 66% and 20% yield respectively the latter hydrocarbon is related to the pentalane class of sesquiterpenoids (see below). A study of this rearrangement, again using a deuteriated substrate, provided evidence for the pathway outlined in Scheme 38. Matsumoto et have also studied the mechanism of formation of the two tricyclic ethers (257) and (260) [with Hg(OAc)2] and the three tricyclic ethers [with Hg(N03)2] derived from humulene after NaBD4 work-up. Under these conditions the five deuteriated products are (266)—(270) respectively. The... 

Formolysis of androsterone tosylate (involving hydride shifts) J. Ramseyer and H. Hirschmann, j. Org. Chem., 32 (1967) 1850). 

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