Grignard reagents with sulphones

Reaction of Grignard reagents with sulphonate derivatives of methyl D-ribofuranoside leads to rearranged, branched-chain sugars as outlined in Scheme 4 anomerization of these compounds by acidic methanolysis or with Grignard reagents was also studied, the latter favouring the thermodynamically less-stable anomers. ... 

The work on vinyl sulphones and their reactions with Grignard reagents, in the presence of transition metal catalysts, all emanates from Julia s laboratory191-195, with the exception of a note196 that presents evidence for SET processes in the alkylation of vinyl sulphones by organometallic reagents. 

Gaoni has published197 a novel preparation of 1,3- and 1,4-dienylic sulphoxides in which certain sulpholenes or sulpholanes can be cleaved with two equivalents of a Grignard reagent. The reactions outlined in equation (86) can be classified formally as a double reduction at the sulphur atom. The 1,4-dienylic sulphoxides can be obtained by the same type of reactions, via bicyclo[3.1.0] sulphones, that are accessible from the sulpholenes and dichlorocarbene, followed by dechlorination with LiAlH4197. Yields for all the reactions are poor to modest (26 to 66%). 

The Grignard reagent derived from benzyl chloride undergoes ready alkylation with an alkyl toluene-p-sulphonate, a reaction which provides a further useful synthesis of an alkylbenzene (e.g. pentylbenzene, Expt 6.2). 

Grignard reagent (144) (R = H or Me) followed by oxidation gave the sulphone (145) which with allyl bromide afforded the acyclic C13 compound (146).92 This gave rise to p-ionone (142) or a- and p-irones (147) and (148), cyclization being achieved with H3P04. p-Cyclogeranyl phenyl sulphide (149) has been prepared... 

Treatment of cyclohexane oxime sulphonates with a methyl Grignard reagent results in a ring-expansion addition of another... 

A rapid method for resolving ( + )-carvone through the derivative (151) has been described. Reaction of carvone with allyl Grignard reagents leads to the expected products (152), and these can be aromatized with toluene-p-sulphonic acid to (153) and (154). An improved method for the preparation of carvone 1,3,8-tribromide [(155) see Vol. 1, p. 31] consists in treating the dibromide (156), obtained by Wallach from dihydrocarvone (148), with phenyltrimethylammonium tribromide in tetrahydrofuran. ... 

Several compounds have been prepared by nucleophilic substitution of chlorine in 2-chloro-l,3-dithian with Grignard reagent (RMgBr), malonic esters, and phenols.A mechanism for the de-ethoxycarbonylation of the 2-(l,3-dithianyl)malonates by sodium chloride or sodium ethoxide has been studied. 2-Chlorotetrahydrofuran reacts with nucleophiles such as 2-lithio-2-phenyl-l,3-dithian (326) by three simultaneous mechanisms i.e. substitution, proton abstraction, and electron transfer) to give the products (327)—(330) (Scheme 12)/° When a dithian (331 R = H or COiMe) was treated with a sulphonyl chloride in pyridine, ring-expansion to the 5//-l,4-dithiepin (332) occurred instead of the expected formation of a sulphonate. ... 

Grignard reagents RMgX into the amines RNH2 succeeds with the former but fails with the latter. The two reagents gave comparable yields in the iV-amination of pyridine and quinoline but for indole and carbazole the first was more effective. It was concluded that, in general, hydroxylamine-O-sulphonic acid was more versatile. 1,2,3-Triazole reacts with hydroxylamine 0-sulphonic acid in aqueous potassium hydroxide to yield a mixture of 53% 1-amino-l,2,3-triazole and 14% of the 2-amino isomer (equation 37) . ... 

---