Tetrahydrofuran, cleavage

A soln. of triphenylgermane in tetrahydrofuran treated with a soln. of allyl-magnesium chloride in tetrahydrofuran, and refluxed 4 days (4-hydroxy-butyl) triphenylgermane. Y 83.4%. H. Gilman and E. A. Zuech, J. Org. Ghem. 26, 3035 (1961) syntheses of silanes by tetrahydrofuran cleavage cf. U. Kriierke, B.95,174 (1962). 

Ethylene also is a by-product of the cleavage reaction with tetrahydrofuran (99). The rate of loss for / -butyUithium in a variety of ether solvents is given in Table 6. 

A one-pot conversion of benzyl alcohols to benzyl fluorides by treatment of the alcohols with a combination of methanesulfonyl fluoride, cesium fluoride and 18-crown 6 ether in tetrahydrofuran has been repotted The reaction involves mesylation of the alcohols followed by cleavage of the resultant mesyl esters with a fluoride ion The reaction has been extended also to certain heterocycles bearing the N hydroxymethyl group [43] (equation 31)... 

Tetrabutylammonium fluoride (TBAF) is usually used in the form of the trihydrate or as a solution in tetrahydrofuran (THF). The pure form is difficult to isolate, owing to decomposition to FFF, tributylamine, and but-l-ene [18, 19] on dehydration. It has been used for a variety of reactions, including as a catalyst for various reactions with silicon compounds [20, 21]. One of its main uses is in the cleavage of silyl ether protecting groups [22]. 

What product would you expect from cleavage of tetrahydrofuran with HI ... 

Intermediate 8, the projected electrophile in a coupling reaction with intermediate 7, could conceivably be derived from iodolactone 16. In the synthetic direction, cleavage of the acetonide protecting group in 16 with concomitant intramolecular etherification could result in the formation of the functionalized tetrahydrofuran ring of... 

A mechanism for its formation was also proposed. Essentially, this involved protonation of 2-methylfuran followed by dimerization and trimerization to a 2,4-difuryl tetrahydrofuran derivative which suffered an acid catalysed cleavage of the saturated ring to produce a carbenium ion possessing an alcoholic function at the other end of... 

The exact time and temperature required for complete reaction must be determined for each individual compound. It has been observed that nucleophilic demethylation of methyl o-alkoxyaryl ethers is accelerated relative to anisole [Benzene, methoxy-],6 and this reaction is no exception. Lithium diphenylphosphide cleavage of anisole is complete in about 4 hours in refluxing tetrahydrofuran, whereas the present reaction is complete within 2 hours at 25°. 

Remarkable solvent effects on the selective bond cleavage are observed in the reductive elimination of cis-stilbene episulfone by complex metal hydrides. When diethyl ether or [bis(2-methoxyethyl)]ether is used as the solvent, dibenzyl sulfone is formed along with cis-stilbene. However, no dibenzyl sulfone is produced when cis-stilbene episulfone is treated with lithium aluminum hydride in tetrahydrofuran at room temperature (equation 42). Elimination of phenylsulfonyl group by tri-n-butyltin hydride proceeds by a radical chain mechanism (equations 43 and 44). 

There are two possible ways for the ring opening of 35 in the polymerization The C1—O7 bond cleavage leads to the formation of a substituted tetrahydropyran ring 36 in the polymer chain, while the C1—O2 bond cleavage produces a substituted tetrahydrofuran ring 37. Product analysis of the acid-catalyzed hydrolysis of the... 

OS 11] [R 36] ]P 10] The feasibility of performing the acylating cleavage of T2-triazene resin (100 mg) in absolute tetrahydrofuran to give piperazine was demonstrated [75] 4 h of processing was required. 

For preparative purposes, titanium metal can be used in place of sodium or lithium in liquid ammonia for both the vinyl phosphate231 and aryl phosphate232 cleavages. The titanium metal is generated in situ from TiCl3 by reduction with potassium metal in tetrahydrofuran. 

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