A,/3-epoxy sulfones

Desulfurization of fl, a-epoxy sulfones 239 prepared from allylic sulfones 238 and m-chloroperbenzoic acid with sodium amalgam leads to the formation of allyl alcohols (240) in good yields (equation 144)138. Allyl alcohols prepared by this method are listed in Table 16. 

Watt and coworkers139 prepared the a-azidoaldehydes (242) by nucleophilic ring opening with sulfinate ion expulsion of a, /(-epoxy sulfones 241 with sodium azide in DMF... 

ENOL ETHERS Trimethylchlorosilane. EPISULFIDES Sulfur monochloride. EPOXIDES Dimethylformamide dimethyl acetal. Dimethyloxosulfonium methylide. Iodine. Methylene bromide-Lithium. Methylphenyl-N-p-toluene-sulfonylsulfoximine. a -EPOXY SULFONES Hydrogen peroxide. 

Table 3 Preparation of a. -Epoxy Sulfones by the Daizens Condensation (equation 8) ...

An interesting new method for the conversion of [I, y-epoxy sulfones (82) to cyclo-alkenones (85) has been developed61. It includes the addition of alkyllithium to y-hydroxy-a,/ -unsaturated sulfones generated from 82 and the alkylation of sulfonyl carbanion thus formed. Oxidation of the resulting y-hydroxy sulfone to 84 followed by elimination of benzenesulfinic acid gives the desired product 85 in good yields (equation 72)61. 

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. ... 

The epoxy-Ramberg-Backlund reaction (ERBR) has been used for the conversion of a,/3-epoxy sulfones into a range of mono-, di-, and tri-substituted allylic alcohols.34 Modification of this method has permitted the preparation of enantio-enriched allylic alcohols following the diastereoselective epoxidation of enantio-enriched vinyl sulfones that were accessed efficiently from the chiral pool. 

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). 

Epoxidation of vinyl sulfones is the most common procedure for the preparation of a,/l-epoxy sulfones514. Organolithium compounds derived from a,/8-epoxy sulfones 336... 

Treatment of epoxy sulfone 118 with LDA (4equiv) in THF at —65°C affords oxocane 119 in 71% yield as a single isomer (Scheme 27) <1998JOC9728, 2001SL117>. 

OL-Hydroxy aldehydes. A new method for one-carbon homologation of ketones to a-hydroxy aldehydes involves Darzens condensation with chloromethyl phenyl sulfone to give an ex,p-epoxy sulfone followed by ring opening by hydroxide ion. The anhydrous potassium hydroxide obtained by controlled addition of water to potassium /-butoxide (8,... 

Reaction of Sulfonyl-Stabilized Oxiranyllitbiums. Reaction of sulfonyl-stabilized oxiranyllitbiums with primary alkyl halides gives acceptable yields of products. More reactive alkyl triflates give generally better yields but, due to the instability of oxiranyl-lithiums, yields are often not reproducible when electrophiles are added to a solution of the preformed oxiranyllitbiums. It is recommended that the alkylation reaction be carried out by an in situ trapping method. Treatment of a solution of epoxy sulfone (1.0 equiv) and triflate (1.5 equiv) in THE-DMPU (or HMPA) at — 100 °C under argon with n-BuLi (1.0 equiv) followed by stirring... 

Related Reagents. Optically active trisubstituted sulfonyl-stabilized oxiranyllithiums can be generated by deprotonation of the corresponding epoxy sulfones (eq 9). Due to the diminished reactivity of the reagents by steric hindrance, the reaction with triflates requires HMPA to obtain a high yield of product (eq 10). ... 

Enantioselective Darzens Reaction. An enantioselective Darzens reaction between ethyl methyl ketone and chloromethyl p-tolyl sulfone in the presence of a chiral ammonium salt derived from (1) and chloromethylpolystyrene affords an optically active a,p-epoxy sulfone in 23% ee. ... 

A novel tandem process has been reported " for the preparation of allylic amines, ethers, and sulfides from a-bromo-a, jS-unsaturated sulfones. The process is believed to proceed via an initial conjugate addition followed by proton exchange and Ramberg-Backlund rearrangement (see Scheme 75). A new variant of the Ramberg-Backlund reaction has been described in which a, /f-epoxy sulfones (319), on treatment with base, are converted into a range of mono-, di-, and tri-substituted allylic alcohols (320). 

Treatment of the epoxy sulfones obtained thus with MgBr2 produces a-bromo ketones or a-bromo al-dehyde. This conversion can be applied to stereoselective preparations of a-bromo methyl ketones from cyclohexanone derivatives. Thus, treatment of 17-P-hydroxy-5-a-androstan-3-one (134) with 1-chloroethyl phenyl sulfone provides an epoxy sulfone (135), which is cleaved by MgBr2 to give a 99 1 mixture of 3-acetyl-3-bromoandrostanes (136 and 137 equation 33), whereas similar treatment of 17-p-hydroxy-5-B-androstan-3-one (138) gives a 4 96 mixture of 3-acetyl-3-bromoandrostanes (139 and 140 equation 34). These facts may reflect the steric course of the initial attack of the a-sulfonyl carbanion on the carbonyl face. 

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-... 

A disadvantage of this procedure is that reductive cleavage of the epoxy sulfones leading to trisub-stituted alkenes, e.g. (95), is not stereoselective. However, formation of disubsituted alkenes follows the trends found in the standard Julia alkenation in that rrani-alkenes are favored (equation 24) and proximate branching increases the stereoselectivity (equation 25). Unlike the standard Julia alkenation, the stereochemistry of the epoxy sulfone reductive elimination depends on the stereochemistry of the precur-... 

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