Tosylates formolysis

In the controversy that developed, the point under attack was not so much the existence of the intermediate bridged ion—although this was questioned, too— as its mode of formation. The 3-phenyl-2-butyl tosylates undergo solvolysis at much the same rate as does unsubstituted e c-butyl tosylate formolysis a little faster, acetolysis a little slower. Yet, as depicted by Cram, phenyl gives anchimeric assistance to the reaction. Why, then, is there no rate acceleration ... 

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. 

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. 

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... 

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... 

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

Formolysis of the 17aa-methyl-D-homo-17 S-tosylate (36), followed by deesterification with LiAlH4, gave the 16-ene (37) as the major product, with small amounts of the two pairs of alcohols epimeric at C-16 (38) and C-17 (39). Predomi-... 

Anchimeric Assistance by Alkyl Groups The formolysis of neopentyl tosylate (612, X=OTs) is as rapid as that of ethyl tosylate whereas the rate of tri-fluoroacetoly sis is enhanced by a factor of 160. These data have been taken as evidence... 

Coates and Bertram developed a 7r-route to usefully substituted compounds potentially convertible by the acyl azide procedure" to atisine derivatives. Iso-steviol (70) was converted to the unsaturated tosylate (71). Buffered formolysis... 

Participation of tt electrons from an adjacent double bond controls the stereochemistry of substitution in the case of cyclopent-3-enyl tosylates, even though no strong rate enhancement is observed. The stereochemistry has been demonstrated by solvolysis of a stereospecifically labeled analog. The product of formolysis is formed with complete retention of configuration, in contrast to the saturated system, which reacts with complete inversion under similar conditions. The retention of configuration is explained by a structure similar to that shown in the case of the anti-7-norbomenyl cation. 

The formation of (562) to the extent of 8 % and the rate enhancement in the formolysis of the homopropargyl tosylate (560) suggest that the cyclopropyli-dene cation (561) is involved. The same product distribution was obtained from (563) (Scheme 75). 

Formolysis of cis-bicyclo[4,l,0]hept-3-yl tosylate followed by reduction gives cyclohept-3-enol as the major (63 %) product. The preparation of 4-chlorocycloheptene from cis-bicyclo[4,l,0]heptan-2-ol is also discussed. ... 

These effects, determined with tertiary chlorides, unquestionably refer to 8n1 reactions so also do Lewis and Boozer s effects on acetolysis and formolysis—-if we can rely on the constancy of the effect of a-deuteration (Table VIII). The /3-effects then suggest that formolysis of the secondary bromide and solvolysis in aqueous ethanol of the tosylate are also SnI—or nearly so, unless bimolecular displacement reactions are also subject to similar isotope effects. Shiner (117) had however already shown that this was not so, since deuteration in the two methyl groups of isopropyl bromide did not lead to an experimentally significant effect on the displacement reaction with ethoxide ion in ethanol. It is thus also reasonable to interpret the very small effect (AAF" = 6 cal.) cited by Lewis (74f) for acetolysis of ethyl-2d8 brosylate as evidence that acetolysis of primary sulfonate esters is borderline if not Sn2. This conclusion, already suggested by the abnormally low a-effect for unassisted acetolysis of phenylethyl tosylate [Table VIII and text of Sec. VA, 2(b) 1 is supported by a similarly... 

The stereospecificity of the uranediol rearrangement is further exemplified by predominant formation of different products in the formolysis of the epimeric 20a-tosylate (359-OTs) (443, 444). That olefin (360) is formed by 1,2-hydrogen and methyl rearrangements (rather than elimination and secondary acid-catalyzed rearrangement) was demonstrated by introduction of deuterium and tritium label at C20. A substantial... 

Hirschmann, F. B., and H. Hirschmann Inversions of Both Adjacent Centers in the Formolysis of a 2,2,6-Trialkylcyclohexyl Tosylate. Formation of a 13a-D-Homo Steroid. J. Organ. Chem. (USA) 38, 1270 (1973). 

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