Phenylsulfonyl groups alkenes

Phenylsulfonylfulminic acid, prepared as outlined in Scheme 110, reacted even with highly hindered alkenes such as tetramethylethylene. The phenylsulfonyl group was easily displaced by a variety of nucleophiles such as methoxide, cyanide and hydride (79JA1319). 

The use of isopropylidine acetals (112) as tethers in the intramolecular Diels-Alder reactions of dienes with alkenes facilitates the formation of civ-fused cycloadducts (113) from an endo transition state (Scheme 41).218 The intramolecular Diels-Alder reaction of 4-[tris-(2-mcthylcthyl)silyl]oxy-2//-thiopyran derivatives with potential dienophiles tethered at C(2), C(3), C(5), and C(6) positions yielded cycloadducts when the dienophiles were activated with a carbomethoxy group.219 By the substitution of a phenylsulfonyl group on the dienophile of 2-benzopyran-3-ones, it is possible to enhance exo addition during intramolecular Diels-Alder cyclizations to yield a predominance of trans-fused hexaphenanthrenes related to natural products.220 The intramolecular Diels-Alder reaction of 2-furfuryl fumarates has been investigated by molecular mechanics (SIBFA)/continuum reaction field computations.221 The intramolecular 4 + 2-photo-cycloaddition of A-benzylcinnamamides (114) in the presence of C(,H6 gives 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4-ones (115) with high stereoselectivity (Scheme 42).222... 

Reaction with -alkylthio nitro olefins. Nitro alkenes bearing an alkylthio or phenylsulfonyl group at the -position undergo addition-elimination reactions with organocopper/zinc reagents to provide functionalized (E)-nitro alkenes. 

There has been a number of developments in the use of salicylaldehydes as precursors of both chromenes and chromans. Alkenes activated by acyl, formyl, nitrile and phenylsulfonyl groups react with 2-hydroxybenzaldehydes and 2-hydroxy-1-naphthaldehyde under Bayliss-Hillman conditions to yield 3-substituted chromenes via the in situ dehydration of the initially formed chroman-4-ol <02JCS(P1)1318>. In like manner, P-nitrostyrenes yield 2- and 2,2-substituted derivatives of 3-nitrochromenes <02H(57)1033>. A simple route to 2-phenyl-2H-chromenes starting from salicylaldehyde and utilising a Pd(0)-catalysed cyclisation of an allylic acetate has been described <02SC3667>. 

The temporary functionalization of cyclic or acyclic alkenes with a phenylsulfonyl group, followed by [4 -t- 2] cycloadditions of 1,3-bis-oxygenated dienes, opens a regiocontrolled route to annulated or 5-substituted cyclohexenones (Scheme 18). ... 

Synthesis of 2-Alkanones and 3-Alken-2-one. Monoalkylation of 4-phenylsulfonyl-2-butanone ethylene acetal 1 takes place at the position a to the phenylsulfonyl group on successive treatment with butyllithium and then with an alkyl halide (or tosylate). Deprotection of the acetal group and subsequent elimination of the benzenesulfinic acid moiety with a base transforms the monoalkylation product to the corresponding 3-alken-2-one (eq 1). A 2-alkanone is obtainable from the monoalkylation product by reductive desulfurization and subsequent acidic deprotection (eq 2) ... 

Cossu S, Peluso P, Alberico E, Marchetti M. Rhodium catalyzed hydroformylation of 2-phenylsulfonylbicyclo[2.2.1] alkenes effect of the phenylsulfonyl group. Tetrahedron Lett. 2006 47 2569-2572. 

The well-known method of furazan formation is based on nitrosation of alkenes. Thus, several NO donor 3,4-disubstituted 1,2,5-oxadiazole 2-oxide derivatives and the related 1,2,5-oxadiazoles, containing methylsulfonylphe-nyl, phenylsulfonyl, sulfonylamidophenyl, and phenylsulfonylamido groups were synthesized by nitration of... 

It should be noted that addition of the tributyltin radical to 1-fluoro-1-(phenylsulfonyl)ethene provides phenyl vinyl sulfone as the only isolated product. However, 2-trimethylsilyl-1-fluoro-1-(phenylsulfonyl)ethene reacts with tributyltin hydride in the presence of AIBN to provide (E)-2-trimethylsilyl-1-fluoro-1-tributylvinylstannane. The vinylstannane is an equivalent for the synthon "H2C=CF " providing a convenient route to 2-fluoro-1-alkenes.8 The trimethylsilyl group can be removed with potassium fluoride in dimethyl sulfoxide-water or oxalic acid-methanol at the end of the reaction sequence. 

Cyclopropanes multiply-substituted with electron-withdrawing groups are prepared by a number of methods (see also Sections III. A. 5, III.B and III. C). The Cu (acac)2-catalyzed or photochemical reactions of alkenes with bis(phenylsulfonyl)methylide, which is easily... 

Dimethoxy-3,6-dihydropyrazine (109), prepared by methylation of 2,5-piperazinedione with trimethyloxonium tetrafluoroborate, is susceptible to lithiation because the protons at C-3 and C-6 are activated by adjacent imine moieties. The lithium salt of this bislactim ether reacts with the 2-chloro-l-phenylsulfonyl alkene (110) to give the 3-substituted pyrazine (111) (Scheme 25) <89JCS(P1)453>. The bislactim ether from piperazinedione cyclo(L-Val—Gly) is lithiated with butyl-lithium and then treated with ketones, alkyl halides, or others to form, nearly stereospecifically, ran5-3-isopropyl-6-substituted piperazinediones due to the steric influence of the isopropyl group <828866, 838673). Similar stereoselective syntheses have been achieved in reactions starting from cyclo(L-Val—D,L-Ala) <828864, 918939). Acid hydrolysis of these products affords chiral a-amino acids. 

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