171868-69-2Relevant academic research and scientific papers
Palladium-Catalyzed Regio- A nd Enantioselective Hydrosulfonylation of 1,3-Dienes with Sulfinic Acids: Scope, Mechanism, and Origin of Selectivity
Dong, Dongfang,Zhang, Qinglong,Zi, Weiwei
supporting information, p. 15860 - 15869 (2020/10/18)
Chiral sulfones are important structural motifs in organic synthesis because of their widespread use in pharmaceutical chemistry. In particular, chiral allylic sulfones have drawn particular interest because of their synthetic utility. However, enantioselective synthesis of 1,3-disubstituted unsymmetrical chiral allylic sulfones remains a challenge. In this article, we report a protocol for (R)-DTBM-Segphos/Pd-catalyzed regio- A nd enantioselective hydrosulfonylation of 1,3-dienes with sulfinic acids, which provides atom- A nd step-economical access to 1,3-disubstituted chiral allylic sulfones. The reaction occurs under mild conditions and has a broad substrate scope. Combined experimental and computational studies suggest that the reaction is initiated by a ligand-to-ligand hydrogen transfer followed by a C-S bond reductive elimination via a six-membered transition state. Steric repulsion between the olefinic C-H of the substrate and the tert-butyl group of (R)-DTBM-Segphos was found to be a key factor in the enantiocontrol.
π-Allylic sulfonylation in water with amphiphilic resin-supported palladium-phosphine complexes
Uozumi, Yasuhiro,Suzuka, Toshimasa
experimental part, p. 1960 - 1964 (2009/04/04)
π-Allylic substitution of allyl esters with sodium arylsul-finate was performed with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported phosphine-palladium complex in water as a single reaction medium under heterogeneous conditions to give allyl sulfones in good to high yields. Catalytic asymmetric allylic substitution of cycloalkenyl esters also took place in water using a PS-PEG resin-supported chiral imidazo-indolephosphine- palladium complex to give cycloalkenyl sulfones with up to 81% ee.
Highly selective palladium catalyzed kinetic resolution and enantioselective substitution of racemic allylic carbonates with sulfur nucleophiles: Asymmetric synthesis of allylic sulfides, allylic sulfones, and allylic alcohols
Gais, Hans-Joachim,Jagusch, Thomas,Spalthoff, Nicole,Gerhards, Frank,Frank, Michael,Raabe, Gerhard
, p. 4202 - 4221 (2007/10/03)
We describe the highly selective palladium catalyzed kinetic resolutions of the racemic cyclic allylic carbonates rac-1a-c and racemic acyclic allylic carbonates rac-3aa and rac-3ba through reaction with tert-butylsulfinate, tolylsulfinate, phenylsulfinate anions and 2-pyrimidinethiol by using N,N′-(1R,2R)-1,2-cyclohexanediylbis[2-(di-phenylphosphino)-benzamide] (BPA) as ligand. Selectivities are expressed in yields and ee values of recovered substrate and product and in selectivity factors S. The reaction of the cyclohexenyl carbonate 1a (≥99% ee) with 2-pyrimidinethiol in the presence of BPA was shown to exhibit, under the conditions used, an overall pseudo-zero order kinetics in regard to the allylic substrate. Also described are the highly selective palladium catalyzed asymmetric syntheses of the cyclic and acyclic allylic tert-butylsulfones 2aa, 2b, 2c, 2d and 4 a - c, respectively, and of the cyclic and acyclic allylic 2-pyrimidyl-, 2-pyridyl-, and 4-chlorophenylsulfides 5aa, 5b, 5ab, 6aa - ac, 6ba and 6bb, respectively, from the corresponding racemic carbonates and sulfinate anions and thiols, respectively, in the presence of BPA. Synthesis of the E-configured allylic sulfides 6aa, 6ab, 6ac and 6bb was accompanied by the formation of minor amounts of the corresponding Z isomers. The analogous synthesis of allylic tert-butylsulfides from allylic carbonates and tert-butylthiol by using BPA could not be achieved. Reaction of the cyclopentenyl esters rac-1da and rac-1db with 2-pyrimidinethiol gave the allylic sulfide 5c having only a low ee value. Similar results were obtained in the case of the reaction of the cyclohexenyl carbonate rac-1a and of the acyclic carbonates rac-3aa and rac-3ba with 2-pyridinethiol and lead to the formation of the sulfides 5 ab, 6 ab, and 6 bb, respectively. The low ee values may be ascribed to the operating of a "memory effect", that is, both enantiomers of the substrate give the substitution product with different enantioselectivities. However, in the reaction of the racemic carbonate rac-1 a as well as of the highly enriched enantiomers la (≥99% ee) and ent-1a (≥99% ee) with 2-pyrimidinethiol the ee values of the substrates and the substitution product remained constant until complete conversion. Similar results were obtained in the reaction of the cyclic carbonates rac-1a, ent-1a (≥99% ee) and ent-1c (≥99% ee) with lithium tert-butylsulfinate. Thus, in the case of rac-1a and 2-pyrimidinthiol and tert-butylsulfinate anion as nucleophiles the enantioselectivity of the substitution step is, under the conditions used, independent of the chirality of the substrate; this shows that no "memory effect" is operating in this case. Hydrolysis of the carbonates ent-1a-c, ent-3aa and ent-3ba, which were obtained through kinetic resolution, afforded the enantiomerically highly enriched cyclic allylic alcohols 9a-c (≥99% ee) and acyclic allylic alcohols 10a (≥99% ee) and 10b (99% ee), respectively.
Rapid and stereoselective C-C, C-O, C-N and C-S couplings via microwave accelerated palladium-catalyzed allylic substitutions
Bremberg, Ulf,Lutsenko, Serghey,Kaiser, Nils-Fredrik,Larhed, Mats,Hallberg, Anders,Moberg, Christina
, p. 1004 - 1008 (2007/10/03)
Palladium-catalyzed substitution of cyclohex-2-en-1-yl ethyl carbonate with neutral C-, O-, and N-nucleophiles was achieved in 1-2 minutes using microwave flash heating. Enantioselectivities up to 96% were observed. Ionic nucleophiles tended to result in
Asymmetric synthesis of allylic sulfones. Useful asymmetric building blocks
Trost, Barry M.,Organ, Michael G.,O'Doherty, George A.
, p. 9662 - 9670 (2007/10/02)
Construction of sulfones in enantiomerically pure form provides a great opportunity to enhance their value as synthetic building blocks. Allylic sulfones, in particular, have great flexibility derived from sulfone-controlled additions to the double bond. Two strategies have been developed based upon the ability to effect asymmetric allylic alkylations with palladium employing ligands derived from C2 symmetric diamines and 2-(diphenylphosphino)-benzoic acid. Desymmetrization of meso-2-ene-1,4-diol diesters does not involve the nucleophile in the enantiodiscriminating step and thus should, a priori, not depend upon the nature of the nucleophile. Indeed, such desymmetrization of such a diester in the presence of a sulfinate anion gave excellent enantioselectivity. On the other hand, conversion of both enantiomeric allylic esters to enantiomerically pure allylic sulfones requires sodium benzenesulfinate to participate in the enantiodiscriminating step. Five-, six-, and seven-membered substrates all gave excellent enantioselectivities. A catalytic phase transfer system proved most efficacious on larger scales. Propagating the asymmetry requires diastereoselective functionalization of the double bond. While epoxidation proved excellent for the five-membered ring case and satisfactory for the six-membered ring case, it was unsatisfactory in the seven-membered ring case. Osmium tetroxide-catalyzed cis-dihydroxylation gave excellent diastereoselectivities in the six- and seven-membered ring cases. Reductive cleavages produced enantiomerically pure allylic alcohols. Base-catalyzed elimination generated enantiomerically pure γ-hydroxy-α,β-unsaturated sulfones from which further stereogenic centers were produced by diastereoselective conjugate additions. Notably, an asymmetric cyclopentenone annulation using palladium-catalyzed cycloadditions now derives from racemic allyl alcohols.
