Triphenylphosphine reaction with epoxides

Reaction with epoxides. Epoxides react with triphenylphosphine and carbon tetrachloride (reflux under N2 for I 2 hr.) to give the corresponding cts-l,2-dichloro-alkane and triphenylphosphine oxide. Thus cyclohexenc oxide is converted into cis-l,2-dichlorocyclohexane in 80% yield. Only a trace of rran -l,2-dichlorocyclo-hexane is formed. 

Episulfides, which can be generated in situ in various ways, react similarly to give P-amino thiols, and aziridines give 1,2-diamines. Triphenylphosphine similarly reacts with epoxides to give an intermediate that undergoes elimination to give alkenes (see the Wittig reaction, 16-47). 

The latter, on reaction with methylamine yielded via the P-epoxide 373, the trans-a aminoalcohol 374, which was N-acylated to the amide 375. Acid-catalysed dehydration of the tertiary alcohol 375, led to the olefin 375, from which the key radical precursor, the chlorothioether377 was secured in quantitative yield by reaction with N-chlorosuccinimide. In keeping with the earlier results recorded for structurally related compounds, 377 on heating in the presence of ruthenium dichloride and triphenylphosphine also underwent a 5-exo radical addition to generate the cyclohexyl radical 378 which recaptured the chlorine atom to furnish the a-chloro-c/5-hydroindolone 379. Oxidation of thioether 379 gave the corresponding sulfoxide 380, which on successive treatment with trifluoroacetic anhydride and aqueous bicarbonate led to the chloro-a-ketoamide 381. The olefin 382 resulting from base induced dehydrochlorination of 381, was reduced to the hydroxy-amine 383, which was obtained as the sole diastereoisomer... 

N-acylaziridines occurs on treatment with triphenylphosphine with the formation of the ylides (67), thereby providing a route to a-substituted primary allylic amines via their in situ reactions with aldehydes.The reactions of triphenylphosphine with epoxides in phenolic media provide a new access to the vinyl-phosphonium salts (68). A route to 1-hydroxyalkylphosphonium salts is provided by the reactions of trimethyl- or triethyl-phosphine with aldehydes or ketones in the presence of anhydrous acids. The related 1-trimethylsiloxyalkylphosphonium salts can be isolated in the presence of trimethylsilyl chloride.Further Wittig-products have been isolated from the reaction of 1,2,3-indanetrione with triphenylphosphine, and, in related work, it has been shown that furoin is deoxygenated on heating with triphenylphosphine to form 2-furfuryl(2-furyl)ketone and triphenylphosphine oxide.The structure of the blue product from the reaction of triphenylphosphine with 2,3,5,6-tetracyano-7-oxabicyclo(2,2,1]hepta-2,5-diene has now been shown by X-ray techniques to be the stable ylide (69). ... 

The mixture of 33, 308, and 309 can be converted to the cyclohexene derivative 310 with a C2 symmetry axis by reaction with triphenylphosphine and triiodoimidazole and by respective osmylation and epoxidation of 310, myo- 33 and chiro-inositols 308 were obtained (Scheme 5-7). ... 

Olefin inversion. This inversion can be accomplished by epoxidation, reaction with triphenylphosphine dibromide or dichloride to give a ic-dihalide, and then /rans-elimination of the added halo groups with zinc-acetic acid (equation I). The sequence involves two inversions, one at each carbon joined to oxygen. ... 

Epoxide Cleavage. Epoxides open by reaction with TMSCl in the presence of Triphenylphosphine or tetra-n-butylammonium chloride to afford O-protected vicinal chlorohydrins (eq 27). ... 

Azides react with epoxides too. This epoxide is one diastereoisomer (trans) but racemic and the symbol ( ) under each structure reminds you of this (Chapter 14). Azide attacks at either end of the three-membered ring (the two ends are the same) to give the hydroxy-azide. The reaction is carried out in a mixture of water and an organic solvent with ammonium chloride as buffer to provide a proton for the intermediate. Triphenylphosphine in water is used for reduction to the primary amine. 

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