Vinylmagnesium chlorides

Vibrational relaxation, 293, 295 17 a-Vinyl-5a-androstane-3 /3,17 /3-diol, 164 Vinyllithium, 64, 163 Vinylmagnesium chloride, 58 4-Vinyltestosterone, 89... 

In the first of these sequences, often called the Torgov-Smith synthesis, the initial step consists in condensation of a 2-alkyl-cyclopentane-l,3-dione with the allyl alcohol obtained from 6-methoxy-l-tetralone and vinylmagnesium chloride. Although this reaction at first sight resembles a classic SN displacement, the reaction is actually carried out with only a trace of base. 

Hydromagnesiation (11, 163-164 12, 168-169). Cp2TiCl2-catalyzed syn-addition of isobutylmagnesium chloride to propargylic alcohols affords a stereoselective route to vinylmagnesium chlorides for further synthetic use. ... 

Di- or tetrahydropyrans with vinyl side chains obtainable by diastereo-selective ring closing metathesis or by addition of vinylmagnesium chloride to appropriately functionalized tetrahydropyranones are converted to spirocyclic hemiacetals under hydroformylation conditions (Scheme 4) [33]. Oxidation yields the corresponding lactones. 

For example, the treatment of 2-butyn-l-ol (45) with allyhnagnesium chloride in refluxing ether followed by hydrolysis affords 46 in 85% yield (Scheme 27) . Although the use of vinylmagnesium chloride also provides the corresponding awfi-addition product in... 

The above procedure is essentially that described previously by the author.2 Di-w-butylvinyltin has been prepared by the reaction between vinylmagnesium chloride with either di-w-butyltin dichloride or di-w-butyltin oxide.6 The preparation of vinylmagnesium bromide was first described by Normant.6... 

Aminopropanols, when reacted with cyanogen bromide, also afford 2-amino-(or imino)-dihydro-1,3-oxazines (Scheme 90) (64ZOB3427), and related thiazines are formed when allylic isothiouronium salts (207) are cyclized with trifluoroacetic acid and stannic chloride. The necessary starting materials are synthesized from aldehydes or ketones by the action of vinylmagnesium chloride and subsequent treatment of the product allyl alcohols (206) first with hydrogen chloride and then with a thiourea (Scheme 91) (77JHC717). 

The interaction of (10) with vinylmagnesium chloride yields, after hydrolysis of the ketal group, 46% of the 3a-vinyl- 17-ketone (lib) and 7% of the 3j8-vinyl-17-ketone (12b). Ethynylation of (10) with potassium acetylide in dimethylformamide or with acetylene and potassium /-amyloxide in f-amyl alcohol-ether gives only the 3a-ethynyl derivative (11c) in 63% and 74% yields, respectively.15... 

A synthesis of benzotriquinacene 396) has recently been described (Scheme 63).36s 366 Vinylmagnesium chloride transformed ketone 380 into vinyl alcohol 393 whose dehydration gave 2-vinyltriquinacene 394). Addition of dimethyl acet-ylenedicarboxylate to 394 followed by dehydrogenation led to adduct 395 which underwent ready saponification and copper-catalyzed decarboxylation to give 396. 

Diketones. Vinylmagnesium chloride, in ihe presence of cuprous chloride as catalyst, reacts with a fatty acid or ester to give a 1,6-diketone, usually in rather low yield (5-55%). Thus the reaction as applied to n-valeric acid (I) gives n-telradecane-5,10-dione (2) in 53% yield. 

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