Sommelet rearrangement

By replication of alternate quaternization and Sommelet rearrangement of A,A-dimethylbenzylamine Cantor and Hauser101 reached finally the fully methylated benzylamine (CH3)5C—CH2N(CH3)2. 

The Stevens and the Sommelet rearrangement have their analogs in rearrangement of sulfonium salts by strong bases. 

Sommelet, Compt. rend. Hebd. Seances Acad. Sci., 205, 56 (1937). 

Rearrangement of benzylmethylphenacylsulfonium bromide to 2-(methyl-thio)-3-phenylpropiophenone occurs analogously to the former in a reaction also described by Stevens and a collaborator 103 

Krollpfeifer and Hartmann104 describe this reaction as follows The sulfonium bromide (40 g) is added to a solution prepared from sodium (8 g) and methanol (580 ml), and the mixture is heated for 1 h on the water-bath. The methanol is then removed in steam, and the residual oily 2-(methylthio)-3-phenylpropiophenone is taken up in ether, dried over calcium chloride, and recovered by evaporation. It crystallizes when rubbed and after recrystallization from ethanol has m.p. 55-56° (yield 81 %). 

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Ammonium ion, JV-(2-thenyl)-N-benzyldimethyl-Stevens and Sommelet rearrangement, 4, 800 Ammonium salts, diallyldialkyl-polymerization, 1, 293 Ammonium salts, 2-pyrrolylmethyl-nucleophilic substitution abnormal, 4, 244 Sommelet rearrangement, 4, 244 Ammonium salts, trimethyl(l,3,5-triazinyl)-applications, 3, 525 Amobarbital, 3, 150 Amodiaquine, 1, 145 Amolanone applications, 4, 708... 

Sommelet rearrangement, intermediate temperatures favor Stevens rearrangement,- and high temperatures promote elimination to form isoindoles. Treatment of 2-methyl-2-o-tolylmethylisoindolinium... 

Chiral bis-lithium amide bases have been used for enantiotopic deprotonation of the sulfonium salt of 1,4-oxathiane 86. The anion undergoes an enantioselective thia-Sommelet rearrangement to afford the 3-substituted-1,4-oxathiane 87. Only bis-lithium amide bases were effective, giving products with high diastereoselectivity and with low to moderate enantioselectivity (Equation 13) <2003TL8203>. 

A cyclic sulfonium salt undergoes a thia-Sommelet rearrangement which results in dearomatization and production of the 2-substituted tetrahydrothiopyran 471 in a diastereoselective fashion (Equation 156) <1998JA841>. 

A mixture of 1-methyl-2-p-methoxybenzyl-3,4-diethyl-3-piperi-deine (156), 1 - methyl- 3,4-diethyl - 4 -p- metho xybenzyl- 2-piperideine (157), and 1-methyl- 2-(2-methyI-5-methoxyphenyl)-3,4-diethyl-3-piperideine (158) was obtained from 1-methyl- 1-p-methoxybenzyl-3,4-diethyl-3-piperideinium chloride (155). Compounds 156 and 157 were formed by the Stevens rearrangement, whereas the formation of compound 158 was due to the Sommelet rearrangement.1296... 

The nitrogen ylides (3.60) are formed as intermediates in the Sommelet rearrangement ". The method is used for the conversion of the tetraalkylammonium halides 3.59 (having hydrogen in an a-position to N) into tertiary aromatic amines 3.61 (Scheme 3.25). 

The ferrocene nucleus proved to be absolutely unable to undergo the rearrangements characteristic of the benzene ring, so the Claisen rearrangement of allyl ferrocenyl ether 291), the benzidine rearrangement of hydrazo-ferrocene 294-296), and the Sommelet rearrangement in the ferrocene series were all unsuccessful. 

Campbell, S. J., Danvish, D. Asymmetric induction in the Sommelet rearrangement of chiral benzylsulfonium salts. Can. J. Chem. 1976, 54,... 

Giumanini, A. G., Trombini, C., Lercker, G., Lepley, A. R. Heterobenzyl quaternary ammonium salts. IV. 2-Thenyl group as terminus and migrating moiety in the Stevens and Sommelet rearrangements of a quaternary ammonium ion. J. Org. Chem. 1976,41, 2187-2193. 

Lepey, A. R., Giumanini, A. G. Stevens and Sommelet rearrangements. Mechanisms of Molecular Migrations 1971, 3, 297-440. 

V-Benzyl-/V,/V-dirnethy Ian Mini urn bromide 30 reacts with sodium amide in liquid ammonia to give both the product of 1,2-shift 33 (Stevens rearrangement) and the ortho-substituted compound 34 (Sommelet rearrangement) via the intermediate ylides 31 and 3254 (equation 13). 

The ylides 31 and 39, the key intermediates of both the Stevens and Sommelet rearrangement discussed above, can be generated also by addition of benzyne 38 to N-alkylamines. Thus, generation of benzyne 38 in the presence of A /V-dimethylbenzylamine... 

The rearrangement of ammonium ylides (Stevens-Sommelet rearrangement) or sulfonium ylides the X-Y fragment is an anion a to a positively charged nitrogen (R3 N- CR2) or sulfur (R2,+S- CR2)... 

On treatment with sodium amide in liquid ammonia, d undergoes a Sommelet rearrangement 188> (or/Ao-rearrangement) 81> to give 7 in 80— 90% yield. Kantor and Hauser 81> initially postulated an ylid mechanism... 

Although the Sommelet rearrangement 1S8> product 29 was initially reported in the decomposition of benzhydryltrimethylammonium hydroxide, 28, the major products result from displacement reactions 71>. Hughes and Ingold 71> studied the decomposition of benzhydryltrimethylammonium hydroxide as a function of concentration. 

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