72863-20-8Relevant articles and documents
A General Photocatalytic Route to Prenylation
Rathnayake, Manjula D.,Weaver, Jimmie D.
supporting information, p. 1433 - 1438 (2019/06/13)
Prenylation is an essential reaction on which nature relies to modify properties of molecules and build terpenoids, but remains a challenging chemical reaction. Aiming to capitalize on recent advances in photocatalysis to easily and cleanly generate a broad range of carbon based radicals, we have developed a prenyl transfer reagent that is captured by transiently generated radicals. The reagent can be made in bulk, is bench stable, and broadly applicable such that it can be used with existing photocatalytic methods with very few changes to reaction conditions. Ultimately, this provides a true drop-in solution for prenylation, expanding the scope of substrates that can be readily prenylated.
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.
Redox-active triazolium-derived ligands in nucleophilic fe-catalysis - Reactivity profile and development of a regioselective o-allylation
Klein, Johannes E. M. N.,Holzwarth, Michael S.,Hohloch, Stephan,Sarkar, Biprajit,Plietker, Bernd
, p. 6310 - 6316 (2013/10/21)
Triazolium-derived N-heterocyclic carbene (aNHC) ligands, which are readily accessible by deprotonation of the corresponding triazolium salts, proved to be versatile ligands in diverse allylic substitution reactions. The corresponding triazolium salts are formed from azides and alkynes through the application of 1,3-dipolar cycloaddition and N-alkylation reactions. The unique property of these ligands is to be zwitterionic in their liberated form and to act as strong redox-active σ-donor ligands. By virtue of these qualities, these ligands enable the development of an unprecedented Fe-catalyzed regioselective aryloxylation of allylic carbonates. Copyright
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.
Selective C - S bond formation via Fe-catalyzed allylic substitution
Jegelka, Markus,Plietker, Bernd
scheme or table, p. 3462 - 3465 (2009/12/05)
In contrast to the formation of C - O and C - N bonds it was only recently that the selective C - S bond formation by means of transition metal complexes moved more into the center of research. This is somewhat surprising given the fact that the sulfur at
Ionic liquid/water as a recyclable medium for Tsuji-Trost reaction assisted by microwave
Liao, Meng-Chun,Duan, Xin-Hua,Liang, Yong-Min
, p. 3469 - 3472 (2007/10/03)
An efficient microwave protocol is described for allylic substitution with various carbon and heteronucleophiles catalyzed by Pd(OAc)2/TPPTS in an [EMIm]BF4/H2O medium. The ionic liquid/water containing catalyst system can be recycled eight times without loss of activity.
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.
Rearrangement of Some Allylic Sulphinate Esters to Allylic Sulphones. Ion-pair and Sigmatropic Shift Mechanisms
Knight, Derek J.,Whitham, Gordon H.,Williams, Jonathan G.
, p. 2149 - 2152 (2007/10/02)
The mechanism of rearrangement of a number of allylic sulphinate esters to the corresponding allylic sulphones on heating in formamide has been investigated as a function of substrate structure.Simple systems such as crotyl and α-methylallyl-sulphinate ap
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
