57647-92-4Relevant academic research and scientific papers
Coupling of Reformatsky Reagents with Aryl Chlorides Enabled by Ylide-Functionalized Phosphine Ligands
Hu, Zhiyong,Wei, Xiao-Jing,Handelmann, Jens,Seitz, Ann-Katrin,Rodstein, Ilja,Gessner, Viktoria H.,Goo?en, Lukas J.
supporting information, p. 6778 - 6783 (2021/02/01)
The coupling of aryl chlorides with Reformatsky reagents is a desirable strategy for the construction of α-aryl esters but has so far been substantially limited in the substrate scope due to many challenges posed by various possible side reactions. This limitation has now been overcome by the tailoring of ylide-functionalized phosphines to fit the requirements of Negishi couplings. Record-setting activities were achieved in palladium-catalyzed arylations of organozinc reagents with aryl electrophiles using a cyclohexyl-YPhos ligand bearing an ortho-tolyl-substituent in the backbone. This highly electron-rich, bulky ligand enables the use of aryl chlorides in room temperature couplings of Reformatsky reagents. The reaction scope covers diversely functionalized arylacetic and arylpropionic acid derivatives. Aryl bromides and chlorides can be converted selectively over triflate electrophiles, which permits consecutive coupling strategies.
Isothiourea-mediated asymmetric functionalization of 3-alkenoic acids
Morrill, Louis C.,Smith, Samuel M.,Slawin, Alexandra M. Z.,Smith, Andrew D.
, p. 1640 - 1655 (2014/03/21)
Isothiourea HBTM-2.1 promotes the catalytic asymmetric α- functionalization of 3-alkenoic acids through formal [2 + 2] cycloadditions with N-tosyl aldimines and formal [4 + 2] cycloadditions with either 4-aryltrifluoromethyl enones or N-aryl-N-aroyl diazenes, providing useful synthetic building blocks in good yield and with excellent enantiocontrol (up to >99% ee). Stereodefined products are amenable to further synthetic elaboration through manipulation of the olefinic functionality.
Application of sulfuryl chloride for the quick construction of β-chlorotetrahydrofuran derivatives from homoallylic alcohols under mild conditions
Zeng, Xianghua,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
supporting information, p. 2391 - 2396 (2013/09/23)
An efficient and mild method is reported for the construction of β-chlorotetrahydrofuran derivatives by 5-endo chlorocycloetherification of homoallylic alcohols. The system employs sulfuryl chloride as the chlorinating agent under catalyst-free conditions. A variety of homoallylic alcohols with aryl or alkyl substituents were smoothly converted into β- chlorotetrahydrofurans in yields up to 98%.
BF3-promoted synthesis of spiroindenyl heterocycles
Chang, Meng-Yang,Lin, Chung-Han,Chen, Yeh-Long,Hsu, Ru-Ting,Chang, Ching-Yao
scheme or table, p. 3154 - 3158 (2010/08/07)
An easy and straightforward synthesis of spiroindenyl heterocycles by the repeated treatment of boron trifluoride etherate (BF3-OEt2) is reported. The overall transformation from ketones 1 to spiro-fused indenes 3 proceeds via Wittig olefination, deconjugation, Grignard addition, and intramolecular electrophilic cyclization in moderate yields. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.
Kinetics and regioselectivity of ring opening of 1-bicyclo[3.1.0] hexanylmethyl radical
Kantorowski, Eric J.,Le, Daniel D.,Hunt, Caleb J.,Barry-Holson, Keegan Q.,Lee, Jessica P.,Ross, Lauren N.
, p. 1593 - 1596 (2008/09/17)
(Chemical Equation Presented) Rate constants for the rearrangement of 1-bicyclo[3.1.0]-hexanylmethyl radical (2) to 3-methylenecyclohexenyl radical (3) and 2-methylenecyclopentyl-1-methyl radical (1) were measured using the PTOC-thiol competition method. The ring-expansion pathway is described by the rate equation, log(k/s-1) = (12.5 ± 0.1) - (4.9 ± 0.1)/θ; the non-expansion pathway is described by log(k/s-1) = (11.9 ± 0.6) - (6.9 ± 0.8)/θ. Employing the slower trapping agent, tri-n-butylstannane, favors methylenecyclohexane over 2-methyl-methylenecyclopentane by more than 120:1 at ambient or lower temperatures.
Microwave-assisted regioselective olefinations of cyclic mono- and di-ketones with a stabilized phosphorus ylide
Wu, Jinlong,Li, Dan,Wu, Huafeng,Sun, Lijie,Dai, Wei-Min
, p. 4643 - 4650 (2007/10/03)
A number of cyclic mono- and di-ketones underwent regioselective olefination with (carbethoxyethylidene)triphenylphospharane under controlled microwave heating. The Wittig reaction of 4-substituted cyclohexanones or 1,2- and 1,4-cyclohexanediones with the ylide at 190 °C for 20 min in MeCN afforded the exocyclic olefins in >94:6 isomer ratios. On the other hand, the same reactions carried out at 230 °C for 20 min in the presence of 20 mol % DBU furnished the endocyclic olefins in >83:17 isomer ratios. The base-mediated isomerization of the exocyclic olefins into the endocyclic isomers was primarily driven by thermodynamic stability of the products and the effect of ring structures on deconjugation was examined.
New application of bromotrimethylsilane: Elaboration of aldehydes/ketones into homologous α,β-unsaturated esters via β-hydroxy esters
Suri, Suresh C.,Marcischak, Jacob C.
, p. 379 - 387 (2007/10/03)
α,β-Unsaturated esters are formed when β-hydroxy esters react with bromotrimethylsilane which is generated from chlorotrimethylsilane- lithium bromide in acetonitrile. Copyright Taylor & Francis, Inc.
Intramolecular cyclization of 2,7- or 2,8-bis-unsaturated esters mediated by (η2-propene)Ti(O-i-Pr)2. Facile construction of mono- and bicyclic skeletons with stereoselective introduction of a side chain. A synthesis of d-sabinene
Urabe,Suzuki,Sato
, p. 10014 - 10027 (2007/10/03)
tert-Butyl 2-en-7-ynoate 6 was treated with (η2-propene)Ti(O-i-Pr)2 (3), generated in situ from Ti(O-i-Pr)4 or Ti(O-i-Pr)3Cl and i-PrMgCl, in ether at -50 to -20°C to afford the product 8 in good yield. The presence of the intermediate titanabicycle 7 was verified by bis-deuterolysis with excess D2O. When the titanabicycle 7 was treated with 1.1 equiv of i-PrOD and then worked up as usual, the monodeuterated product 10 was obtained with high sight selectivity and stereoselectivity. Other electrophiles such as aldehydes and ketones also reacted with the titanabicycle in a highly stereoselective manner to give cyclopentanes having a stereo-defined side chain. On the contrary, treatment of the corresponding ethyl ester, ethyl 8-(trimethylsilyl)-(E)-2-octen-7-ynoate (28), with 3 under the same conditions followed by the addition of 1.1 equiv of s-BuOH afforded 2-(trimethylsilyl)-1-bicyclo[3.3.0]- octen-3-one (32) in 80% yield. Quenching the same reaction mixture with i-PrOD, EtCHO, and Et2CO in place of s-BuOH gave 4-deuterio (with exclusive deuterium incorporation), 4-(1-hydroxypropyl), and 4-(1-ethyl-1-hydroxypropyl) derivatives of the above bicyclic ketone (34, 35, and 36) in good yields. These electrophiles were always introduced from the convex face of the bicyclic skeleton. The stereochemistry of the cyclization could be controlled by an allylic substituent such as (tert-butyl)dimethylsiloxy or butyl group to a high degree yet with a reversal diastereoselection to give 45 or 47. The reaction of ethyl 7-octen-2-ynoate (56) and 3 at -50 to 0°C took place in a quite different way to afford 1-[(ethoxycarbonyl)methyl]bicyclo[3.1.0]hexane (64) in 74% yield after hydrolysis. If the simple hydrolysis is replaced by deuterolysis or the action of diethylketone, 1-[(ethoxycarbonyl)dideuteriomethyl] (with 99% deuterium incorporation), or 1-[(ethoxycarbonyl)(3-pentylidene)methyl] derivative of the above product (65 or 66) was obtained in good yields. A 7-en-2-ynoate having an internal Z-double bond such as 80 afforded a single stereoisomer 82 with the substituent at the endo position, of the bicyclic skeleton, suggesting that the stereochemical integrity of the Z-double bond of the starting material was retained in the product. An alkyl substituent at the allylic position of the substrates like 74 and 76 nicely controlled the stereochemistry of the cyclization to afford single products 75 and 77 with the substituent being placed in the exo orientation of the bicyclic structure. This high diastereoselectivity was successfully applied to an enantioselective synthesis of d-sabinene from an optically active enynoate via nearly complete chirality transfer.
Homolytic Displacement at Saturated Carbon: Part 5. Synthesis of Cyclopropylmethyl, Bicyclohex-2-yl, Bicyclohept-2-yl and Cyclohexanespirocycloprop-2-yl Sulphones from the Corresponding But-3-enylcobaloximes
Gupta, B. Dass,Das, Indira,Dixit, Vandana
, p. 2409 - 2446 (2007/10/02)
But-3-enylcobaloxime reacts with arenesulphonyl chlorides under thermal and photochemical conditions to give cyclopropylmethyl sulphones.The yields depend upon the reaction conditions used.Similar reactions of cyclopent-2-enylmethylcobaloxime and cyclohex-2-enylmethylcobaloximes under photochemical conditions form a mixture of cis and trans isomers of bicyclohex-2-yl and bicyclohept-2-yl sulphones in (50:50) and (70:30) isomeric ratios respectively.However, cyclohex-3-enylcobaloximes form only the trans-bicyclohex-2-yl sulphone.Exclusive formation of cycloalkanespirocycloprop-2-yl sulphones is observed in the reactions of 2-(cyclo alk-1-enyl)ethylcobaloximes with arenesulphonyl chlorides.The reactions are free radical in nature and are believed to take place by a chain mechanism.In the key step a homolytic attack of the RSO2 radical at the terminal (δ) carbon of the butenyl ligand leads to the cyclized product.The exact nature of the ring closure step is uncertain, as both concerted and stepwise mechanisms are possible.
