Sulfones, epoxy synthesis

Koh, Y.J. and Oh, D.Y., A new synthesis of (f-ketophosphonates from aryl epoxy sulfones and dialkyl hydrogen phosphite, Tetrahedron Lett., 34, 2147, 1993. 

This procedure describes a recently reported extension of this reagent and catalyst system for the preparation of epoxysulfones (1) and exemplifies this with the synthesis of multifunctional epoxy sulfone (2) in good ee. ... 

Next step of this synthesis consisted in the conversion of alcohol (17) to pisiferic acid (1) and this has been described in Fig. (3). The alcohol (17) in hexane was treated with Pb(OAc)4 in presence of iodine at room temperature to obtain the epoxy triene (19) (51%) whose structure was confirmed by spectroscopy. Treatment of (19) with acetyl p-toluene-sulfonic in dichloromethane yielded an olefinic acetate (20) and this was hydrogenated to obtain (21). The compound (22) could be isolated from (21) on subjection to reduction, oxidation and esterification respectively. The conversion of (22) to (23) was accomplished in three steps (reduction with sodium borohydride, immediate dehydration in dichloromethane and catalytic hydrogenation). Demethylation of (23) with anhydrous aluminium bromide and ethanethiol at room temperature produced pisiferic acid (1). Similar treatment of (23) with aluminium chloride and ethanethiol in dichloromethane yielded methylpisiferate (3). 

Spirocyclization of an epoxy sulfone,J A short synthesis of nitramide (3) involves as the key step the reaction of the epoxy sulfone 1 with 2 equiv. of BuLi in THF/HMPA (9 1) to form the spirocycle 2 (73% yield). Both the sulfone and sulfonamide groups are cleaved by freshly prepared sodium amalgam (7,326-327). 

Other applications of carbanions a to a sulfone in total syntheses have recently been reported. Most of them used allylic sulfones or allylic halides. Two examples are reported here. In the synthesis of a precursor of cembranolides, a sulfone derived from geranyl bromide was coupled with an allylic alcohol epoxide (Scheme 65). An interesting point was that the coupling reaction gave high yields only when the lithiated sulfone was allowed to react with the epoxymagnesio alkoxide (the lithium salt of the epoxy alcohol did not react at all with the lithiated sulfone). 

The synthesis of the preceding vinyl amino sulfone offers a very good example of a stereospecific sulfide-directed epoxidation (Scheme 76).Oxidation of optically active sulfide alcohol (12 readily made from epoxycyclopentadiene and resolved) with MCPBA affords the corresponding sulfoxide, which is in equilibrium with the sulfenate ester. Treatment with pyridine hydrobromide and then phenyl disulfide and bromine gives the bromodiol (13), which is simply cyclized to the epoxide with aqueous sodium hydroxide solution (83% overall yield from the sulfoxide). Treatment of the P-epoxy sulfone with DBU followed by in situ silylation with f-butyldiphenylsilyl chloride affords an 86% yield of vinyl sulfone (14). Mesylation of the alcohol moiety followed by immediate treatment with dimethylamine produces the amino vinyl sulfone via a syn Sn2 substitution. ... 

A three-stage synthesis of allylic alcohols has been devised (Scheme 32)," which consists of (i) alkylation of a sulfone-stabilized allylic carbanion (ii) peroxy acid oxidation of the allylic sulfone to give a 2,3-epoxy sulfone and (iii) reductive elimination of the 2,3-epoxy sulfone to give the allylic alcohol. The overall strategy is similar to that of the Evans-Mislow allylic alcohol synthesis based on the 2,3-sig-matropic rearrangement of allylic sulfoxides. However, there are regiochemical advantages to the sul-... 

Application of the above mentioned epoxy sulfone cyclization reaction has been ingeniously used in a synthesis of muscone (Scheme 113, entries c and d) and also of vitamin D3 (Scheme 113, entry e)/ In the latter case surprisingly the terminal epoxide, when subjected to the intramolecular cyclization gave a mixture of sulfonylcyclopentane and sulfonylcyclohexane derivatives arising respectively from the epoxide ring opening at the most (30%) and the least (50%) substituted carbons. ... 

J. L. Acena, O. Aijona, R. Manas, and J. Plumet, Unexpected one-pot epoxy sulfone-enaminone transformation. Synthesis of 5a-carba- 3-mannopyranosylamine, J. Org. Chem., 65 (2000) 2580-2582. 

Methyl 2Z,5-hexadienoate (126) undergoes cyclization to / S-parasorbic acid when treated with polyphosphoric acid. Torssell and his co-workers employed the substrate thus obtained for a new series of sugar synthesis. OL-Desosamine was synthesized in an essentially similar way to that described above. Analogously, DL-chalcose (127, 4,6-dideoxy-3-0-methyl-DL-xy/o-hexopyranose), was obtained, that is, by oxirane ring opening in racemic epoxy-lactone 122 with methanol in the presence of p-toluene-sulfonic acid. 

CyehfragmentotioH of epoxy sulfones. Swiss chemists have developed this new method of ring expansion for a synthesis of muscone (7). The starting material was c clododecanone (1), which was converted by known reactions into the hydroxy sulfone (2). Dehydration of (2) results in (3) as the major product. This is epoxidized to give (4), together with the isomeric epoxy sulfone. 

Bis-(4-chlorophenyl)-sulfone is an important intermediate, which is used mainly for the preparation of aromatic poly(sulfone)s and for the synthesis of bis-(aminophenyl)-sulfone. This compound is required both for the therapy of leprosy and for curing epoxy resins. 

Hed Hedrick, J. L., Yilgor, I., Jurek, M., Hedrick. J. C., Wilkes, G. L., McGrath, J. E. Chemical modification of matrix resin networks with engineering thermoplastics 1. Synthesis, morphology, physical behaviour and toughening mechanisms of poly (arylene ether sulfone) modified epoxy networks. Polymer 32 (1991) 2020-2032. 

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