54897-36-8Relevant academic research and scientific papers
Isomerisation of Vinyl Sulfones for the Stereoselective Synthesis of Vinyl Azides
Collins, Niall,Connon, Robert,Evans, Paul,Sánchez-Sanz, Goar
supporting information, p. 6228 - 6235 (2020/10/02)
Reported is the construction, and facile base-mediated conversation of ten differently substituted 3-azido E-vinyl sulfones (γ-azido-α,β-unsaturated sulfones) into their isomeric vinyl azide counterparts. The requisite 3-azido E-vinyl sulfones were prepared from 3-bromo E-vinyl sulfones, which in turn were accessed from allyl sulfones via a bromination-elimination sequence. In relation to this a one-pot azidation-isomerisation sequence was developed which enabled the direct formation of the vinyl azides from the corresponding 3-bromo E-vinyl sulfones. Similarly, a convenient one-pot Horner–Wadsworth–Emmons olefination-isomerisation approach was utilised in order to prepare some of the allylic sulfones used in this study. The vinyl azide forming process typically proceeded with high levels of Z-selectivity, although this was dependent on the vinyl sulfone substitution pattern. Thus, with either no substituent or a methyl group in the γ- or β-position, relative to the sulfone, good, to high levels of Z-selectivity (Z/E = 85:15 to ≥ 95:5) were obtained. However, incorporation of an α-sulfonyl methyl substituent led to an E-selective process (Z/E = 20:80). A non-bonding interaction between the azido group and the α-sulfonyl vinylic proton is proposed, which acts as a conformational control mechanism to help guide the stereochemical outcome.
Tungsten-Catalyzed Allylic Substitution with a Heteroatom Nucleophile: Reaction Development and Synthetic Applications
Xu, Yaoyao,Salman, Muhammad,Khan, Shahid,Zhang, Junjie,Khan, Ajmal
, p. 11501 - 11510 (2020/10/12)
A tungsten-catalyzed allylic allylation of sodium sulfinate as the heteroatom nucleophile was developed. The reaction utilizes inexpensive and readily available (CH3CN)3W(CO)3 as a precatalyst and proceeds at 60 °C temperature in the presence of 2,2′-bipyridine and its derivatives as ligand. The synthetic utility of allylic sulfones as electrophile was further demonstrated through Suzuki-Miyaura cross-coupling as showcased by the formal synthesis of (±)-hinokiresinol.
Cobalt-Catalyzed Allylic Alkylation Enabled by Organophotoredox Catalysis
Takizawa, Koji,Sekino, Tomoyuki,Sato, Shunta,Yoshino, Tatsuhiko,Kojima, Masahiro,Matsunaga, Shigeki
supporting information, p. 9199 - 9203 (2019/06/04)
Co-catalyzed allylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co-catalyzed allylic alkylation using an in situ catalyst activation by organophotoredox catalysis. This noble-metal-free catalytic system exhibits unprecedentedly high reactivities and regioselectivities for the allylation with an allyl sulfone, for the first time, representing the unique synthetic utility of the Co-catalyzed method compared to the related Rh- and Ir-catalyzed reactions.
Chiral Lithiated Allylic α-Sulfonyl Carbanions: Experimental and Computational Study of Their Structure, Configurational Stability, and Enantioselective Synthesis
Gerhards, Frank,Griebel, Nicole,Runsink, Jan,Raabe, Gerhard,Gais, Hans-Joachim
supporting information, p. 17904 - 17920 (2015/12/08)
X-ray crystal structure analysis of the lithiated allylic α-sulfonyl carbanions [CH2=CHC(Me)SO2Ph]Li-diglyme, [cC6H8SO2tBu]Li-PMDETA and [cC7H10SO2tBu]Li-PMDETA showed dimeric and monomeric CIPs, having nearly planar anionic C atoms, only O-Li bonds, almost planar allylic units with strong C-C bond length alternation and the s-trans conformation around C1-C2. They adopt a C1-S conformation, which is similar to the one generally found for alkyl and aryl substituted α-sulfonyl carbanions. Cryoscopy of [EtCH=CHC(Et)SO2tBu]Li in THF at 164K revealed an equilibrium between monomers and dimers in a ratio of 83:17, which is similar to the one found by low temperature NMR spectroscopy. According to NMR spectroscopy the lone-pair orbital at C1 strongly interacts with the C=C double bond. Low temperature 6Li,1H NOE experiments of [EtCH=CHC(Et)SO2tBu]Li in THF point to an equilibrium between monomeric CIPs having only O-Li bonds and CIPs having both O-Li and C1-Li bonds. Ab initio calculation of [MeCH=CHC(Me)SO2Me]Li-(Me2O)2 gave three isomeric CIPs having the s-trans conformation and three isomeric CIPs having the s-cis conformation around the C1-C2 bond. All s-trans isomers are more stable than the s-cis isomers. At all levels of theory the s-trans isomer having O-Li and C1-Li bonds is the most stable one followed by the isomer which has two O-Li bonds. The allylic unit of the C,O,Li isomer shows strong bond length alternation and the C1 atom is in contrast to the O,Li isomer significantly pyramidalized. According to NBO analysis of the s-trans and s-cis isomers, the interaction of the lone pair at C1 with the π orbital of the CC double bond is energetically much more favorable than that with the "empty" orbitals at the Li atom. The C1-S and C1-C2 conformations are determined by the stereoelectronic effects nC-σSR interaction and allylic conjugation. 1H DNMR spectroscopy of racemic [EtCH=CHC(Et)SO2tBu]Li, [iPrCH=CHC(iPr)SO2tBu]Li and [EtCH=C(Me)C(Et)SO2tBu]Li in [D8]THF gave estimated barriers of enantiomerization of ΔG≠=13.2kcal mol-1 (270K), 14.2kcal mol-1 (291K) and 14.2kcal mol-1 (295K), respectively. Deprotonation of sulfone (R)-EtCH=CHCH(Et)SO2tBu (94 % ee) with nBuLi in THF at -105 °C occurred with a calculated enantioselectivity of 93 % ee and gave carbanion (M)-[EtCH=CHC(Et)SO2tBu]Li, the deuteration and alkylation of which with CF3CO2D and MeOCH2I, respectively, proceeded with high enantioselectivities. Time-dependent deuteration of the enantioenriched carbanion (M)-[EtCH=CHC(Et)SO2tBu]Li in THF gave a racemization barrier of ΔG≠=12.5kcal mol-1 (168K), which translates to a calculated half-time of racemization of t1/2=12min at -105 °C.
α-Sulfonyl succinimides: Versatile sulfinate donors in Fe-catalyzed, salt-free, neutral allylic substitution
Jegelka, Markus,Plietker, Bernd
, p. 10417 - 10430 (2011/10/31)
Allyl sulfones are versatile intermediates in organic chemistry. The presence of two distinct functional groups sets the stage for a plethora of subsequent transformations. However, despite these advantages the preparation of regioisomerically enriched sulfones is not easy. The use of sulfinate salts as nucleophiles in substitutions is frequently accompanied by side reactions such as π-bond migration, β-elimination, and so on. Herein we present a preparatively simple way to synthesize a variety of different aryl or alkyl allyl sulfones starting from readily accessible allylic carbonates. By employing aryl or alkyl α-sulfonyl succinimides as sulfinate synthons, mild and regioselective ipso substitution of diverse allylic carbonates was realized.
Example of thermodynamic control in palladium-catalyzed allylic alkylation. evidence for palladium-assisted allylic C-C bond cleavage
Nilsson, Ylva I.M.,Andersson, Pher G.,B?ckvall, Jan-E.
, p. 6609 - 6613 (2007/10/02)
Pd(0)-catalyzed reactions of a number of dienyl acetates with dialkyl malonates show that the regiochemistry of the reaction is very dependent on the reaction conditions. At low temperature and short reaction times the reaction is under kinetic control, but at elevated temperature and longer reaction times the reaction is under thermodynamic control. Under the latter conditions it was demonstrated that the kinetic allylic malonate rearranged to its thermodynamically more stable regioisomer in the presence of the Pd(0) catalyst. The results strongly support the cleavage of an allylic C-C bond by Pd(0), and thus the dialkyl malonate anion has acted as a leaving group.
Regioselective Preparation of Allylic Sulfones by Palladium-Catalyzed Reactions of Allylic Nitro Compounds with Sodium Benzenesulfinate
Ono, Noboru,Hamamoto, Isami,Kawai, Takashi,Kaji, Aritsune,Tamura, Rui,Kakihana, Masato
, p. 405 - 410 (2007/10/02)
Treatment of allylic nitro compounds with sodium benzenesulfinate in the presence of 5 molpercent of Pd(PPh3)4 in N,N-dimethylformamide (DMF) at 20-70 deg C for 1-10 h resulted in the formation of allylic sulfones with predominance of kinetically controll
Palladium-Catalyzed Substitutions of Allylic Nitro Compounds. Regiochemistry
Tamura, Rui,Kai, Yoshiki,Kakihana, Masato,Hayashi, Koji,Tsuji, Masanori,et al.
, p. 4375 - 4385 (2007/10/02)
Primary, secondary, and tertiary allylic nitro compounds underwent Pd(0)-catalyzed allylic substitution by stabilized carboanions, secondary amines, and benzenesulfinate ion (PhSO2-). α,β-disubstituted α-nitro olefins also behaved as allylic nitro compounds, via base-catalyzed vinyl -> allyl rearrangement, and underwent allylic substitution by secondary amines and PhSO2-.The regiochemistry of these substitutions was dependent on the structure of the allylic nitro compound amd on the steric bulk of the nucleophile.Generally, substitution occurred at the lesshindered or least substituted site.In some cases added or generated NaNO2 affected the regioselectivity of the allylic substitution of allylic nitro compounds and some allylic acetates by PhSO2-.Under these conditions, the more sterically hindered allylic sulfones were formed.
Free-Radical Chain Substitution Reactions (SH2') of Alkenyl-, Alkynyl-, and (Alkenyloxy)stannanes
Russell, Glen A.,Herold, Lourdes Lucas
, p. 1037 - 1040 (2007/10/02)
Free-radical chain substitution reactions of allyltributylstannane were observed with PhSSPh, PhCH2SSCH2Ph, PhSeSePh, PhSO2Cl, n-PrSO2Cl, or CCl3SO2Cl, where the attacking radicals leading to allylic rearrangement with displacement of Bu3Sn(radical) were PhS(radical), PhCH2S(radical), PhSe(radical), PhSO2(radical), n-PrSO2(radical), and CCl3(radical), respectively.Allylic rearrangement was also observed in the SH2' reaction of crotyltributylstannane with PhSSPh, PhCH2SSCH2Ph, PhSO2Cl, or n-PrSO2Cl.Propargyltriphenylstannane underwent SH2' substitution to form the allenic substitution products with PhSO2Cl, n-PrSO2Cl, CCl4, and CHCl3 while 2-butynyltriphenylstannane formed the 1,2-butadiene with PhSO2Cl or n-PrSO2Cl.Reaction of (1-cyclohexenyloxy)tributylstannane with CCl4 or BrCCl3 formed α-(trichloromethyl)cyclohexanone.With HCBr3 the initially formed α-(dibromomethyl)cyclohexanone readily underwent dehydrobromination to form α-(bromomethylene)cyclohexanone. tributylstannane formed α-(trichloromethyl)isobutyraldehyde with CCl4 or BrCCl3.Reaction with HCBr3 gave a mixture of α-(dibromomethyl)isobutyraldehyde and 1-(dibromomethyl)-2,2-dimethyloxirane.
