Organic synthesis with sulfones XXXII. A convenient route to α,β -unsaturated sulfones from saturated sulfones.

α-sulfonyl litiated anions are oxidized by cupric carboxylates into β, β-unsaturated sulfones. Primary sulfones lead to pure trans-vinylic sulfones.     

Studies on hydrozirconation of 1-alkynyl sulfoxides or sulfones and the application for the synthesis of stereodefined vinyl sulfoxides or sulfones

The hydrozirconation reaction of 1-alkynyl sulfoxides or sulfones with Cp2Zr(H)Cl in THF at room temperature predominantly gave Z-beta-zirconated vinyl sulfoxides or sulfones with excellent regioselectivity. Compared with 1-alkynyl sulfoxides, the hydrozirconation reaction of 1-alkynyl sulfones exhibits great synthetic potential, leading to the efficient preparation of Z-beta-halovinyl sulfones, Z-beta-sulfonyl alpha,beta-unsaturated ketones, and Z-beta-alkynyl vinyl sulfones. Although the reaction mechanisms are still not clear, the neighboring group participation of the sulfinyl or sulfonyl group may be playing an important role in this unique hydrozirconation reaction.     

Enantioselective synthesis of chiral sulfones by Rh-catalyzed asymmetric addition of boronic acids to alpha,beta-unsaturated 2-pyridyl sulfones

A general and efficient method for the rhodium-catalyzed enantioselective catalytic conjugate addition of organoboronic acids to alpha,beta-unsaturated sulfones is described. The success of the process relies on the use of alpha,beta-unsaturated 2-pyridyl sulfones as key metal-coordinating substrates; typical sulfones such as vinyl phenyl sulfones are inert under the reaction conditions. Among a variety of chiral ligands, Chiraphos provided the best asymmetric induction. This rhodium [Rh(acac)(C2H4)2]/Chiraphos catalyst system has a broad scope, being applicable to the addition of both aryl and alkenyl boronic acids to cis and trans alpha,beta-unsaturated 2-pyridyl sulfones. In most cases, especially in the addition of aryl boronic acids, the reactions take place cleanly and with high enantioselectivity, affording chiral beta-substituted 2-pyridyl sulfones in good yields and enantioselectivities (70-92% ee). The sense and magnitude of this enantioselectivity have been studied by DFT theoretical calculations of the aryl-rhodium insertion step. These calculations strongly support the formation of a five-membered pyridyl-rhodium chelated species as the most stable complex after the insertion into the C=C bond. These highly enantioenriched chiral sulfones are very appealing building blocks in enantioselective synthesis. For instance, the straightforward elimination of the 2-pyridylsulfonyl group by either Julia-Kociensky olefination or alkylation/desulfonylation sequences provides a variety of functionalized chiral compounds, such as allylic substituted alkenes or beta-substituted ketones and esters.     

Synthesis of cyclic sulfones by ring-closing metathesis

A general and highly efficient synthesis of cyclic sulfones based on ring-closing metathesis has been developed. The synthetic utility of the resulting cyclic sulfones was demonstrated by their participation in stereoselective Diels-Alder reactions and transformation to cyclic dienes by the Ramberg-B?cklund reaction.     

An efficient Cu-catalyzed microwave-assisted synthesis of diaryl sulfones

An efficient and microwave-assisted simple protocol for the synthesis of symmetrical/asymmetrical diaryl sulfones through the Cu(II)-catalyzed reaction of sodium salt of sulfinic acid with aryl boronic acid has been described. Various diaryl sulfones have been synthesized in very short reaction times with moderate to very good yields. Additionally, the method is also useful for the synthesis of aryl vinyl sulfones.     

Convenient synthesis of α,β-unsaturated sulfones via a Mizoroki-Heck reaction of arylboronic acids with phenyl vinyl sulfones

Palladium acetate catalyzed Mizoroki-Heck reaction of arylboronic acids with phenyl vinyl sulfones afford α,β-unsaturated sulfones in good yields.     

Synthesis of C2-symmetric bis-indolyl sulfones

A new class of C₂-symmetric bis-indole derivatives with 2,2′-linkage has been synthesized from bis-propargyl sulfones. The method involves treatment of the sulfones with catalytic amount of triethylamine to form the indole derivatives presumably via the intramolecular Michael addition to the intermediate bis-allenic sulfones. Interestingly, the expected Garratt-Braverman pathway was not followed.     

Chemoselective mono halogenation of β-keto-sulfones using potassium halide and hydrogen peroxide; synthesis of halomethyl sulfones and dihalomethyl sulfones

The synthesis of α-halo β-keto-sulfones using potassium halide and hydrogen peroxide as a chemoselective mono halogenation reagent and the synthesis of α,α-symmetrical and asymmetrical dihalo β-keto-sulfones and α-halo, α-alkyl and β-keto-sulfones is described. Base induced cleavage of α-halo β-keto-sulfones, α,α-dihalo β-keto-sulfones, and α-halo, α-alkyl β-keto-sulfones afforded the corresponding halomethyl sulfones, dihalomethyl sulfones and haloalkyl sulfones.     

Reduction of propargylic sulfones to (Z)-allylic sulfones using zinc and ammonium chloride

Propargylic sulfones can be cis-hydrogenated using commercial zinc powder and ammonium chloride in THF-water at room temperature, the major products being the corresponding (Z)-allylic sulfones. Other reducible groups (alkene, benzyloxy) are not affected. Allenylsulfones are implicated in one of the possible reaction pathways.     

Luminescence of some sulfur-containing heterocycles and their sulfones

The luminescence spectra (of crystals and toluene solutions) and the absolute quantum yields of the fluorescence of thianaphtheno[3, 2-b] -thianaphthene, tetraphenylthiophene, 2-phenylthianaphthene, and their sulfones have been measured. The oxidation of the sulfur heterocycles to the corresponding sulfones leads to a marked decrease in the intensity of their luminescence.     

Tautomerism in some quinaldyl sulfones

A series of quinaldyl sulfones was synthesized and their tautomeric composition was determined by ¹H nmr.     

Cross-metathesis reaction of vinyl sulfones and sulfoxides

Cross-metathesis reactions of α,β-unsaturated sulfones and sulfoxides in the presence of molybdenum and ruthenium pre-catalysts were tested. A selective metahesis reaction was achieved between functionalized terminal olefins and vinyl sulfones by using the ‘second generation’ ruthenium catalysts 1c-h while the highly active Schrock catalyst 1b was found to be functional group incompatible with vinyl sulfones. The cross-metathesis products were isolated in good yields with an excellent (E)-selectivity. Both the molybdenum and ruthenium-based complexes were, however, incompatible with α,β- and β,γ-unsaturated sulfoxides.     

Synthesis of allyl sulfones from potassium allyltrifluoroborates

Potassium allyltrifluoroborates underwent a bora-ene reaction with sulfur dioxide in the absence of Lewis acid catalysts to give sulfinyloxy-trifluoroborates, which subsequently undergo alkylation with electrophiles to produce sulfones in up to 91% yield. Benzyl halides and haloacetic acid derivatives can be used as the alkylation reagents while the Sanger reagent undergoes a S_NAr reaction with sulfinyloxy-trifluoroborates to produce the corresponding 2,4-dinitrophenylsulfone. The developed method allows the transformation of potassium allyltrifluoroborates into allyl sulfones.     

One-pot synthesis of aryl biaryl sulfones

Synthesis of aryl biaryl sulfones 3 with good yields is described. The one-pot efficient synthetic route is carried by the NaH-mediated tandem [C3+C3] annulations of cinnamaldehydes 1 and propargylic sulfones 2 under the boiling THF conditions.     

S(N)2' addition/1,2-elimination of dimethylsulfonium methylide with epoxy vinyl sulfones: synthesis of exocyclic cross-conjugated dienyl sulfones

Dimethylsulfonium methylide undergoes S(N)2' addition/1,2-elimination with epoxy vinyl sulfones to generate enantiopure six and seven membered cross-conjugated hydroxy vinyl sulfones. Moderate to excellent yields were obtained for both six and seven membered substrates.     

1，2－联烯亚砚和1，2－联烯砜的反应

1，2－联烯亚砜和1，2－联烯砜是重要的含硫联烯化合物，综述了1，2－联烯 亚砜和1，2－联烯砜的亲核加成、亲电加成、Diels-Alder反应、1，3－偶极加成 、[2+2]环加成等反应以及在天然产物中的应用。     

Organic syntheses with sulfones noxxxvi: conversion of sulfones into aldehydes and ketones.

Alkyl and allyl sulfones can be converted into boronic esters, oxidation of which leads to aldehydes or ketones.     

Conversion of cyclic vinyl sulfones to transposed vinyl phosphonates

Functionalized cyclic vinyl sulfones were directly converted to the "polarity reversed" vinyl phosphonates through an efficient one pot procedure. Ozonolysis of these vinyl sulfones and vinyl phosphonates furnish complementary sets of termini-differentiated ester-aldehydes. This strategy has been applied for preparation of segments needed for the synthesis of Aplyronine A. The scope and limitations of this transformation were defined.     

Palladium-catalyzed benzylic direct arylation of benzyl sulfones with aryl halides

An effective palladium catalyst system for the direct arylation of benzyl sulfones with aryl halides has been developed. The catalytic reaction provides a facile route to diarylmethyl sulfones. The products can be transformed further via desulfonylative functionalization mediated by aluminum compounds.     

New synthesis of allylidenecyclobutanes by the reaction of cyclobutylmagnesium carbenoids with vinyl sulfones

The reaction of cyclobutylmagnesium carbenoids, which were generated from 1-chlorocyclobutyl p-tolyl sulfoxides with EtMgCl via the sulfoxide-magnesium exchange reaction at low temperature, with carbanions derived from vinyl sulfones with n-BuLi or LDA resulted in the formation of allylidenecyclobutanes in moderate to good yields. The actual reactive species of the sulfones in this reaction were proved to be the lithium α-sulfonyl carbanion of allyl sulfones derived from the vinyl sulfones by double bond migration with the bases used. Mono- and di-substituted allylidenecyclobutanes can be obtained by using a variety of vinyl sulfones.