110474-43-6Relevant articles and documents
Realization of high regioselectivity in the coupling reaction of a cyclopentadiene monoepoxide equivalent and aryl nucleophiles
Kobayashi, Yuichi,Takahisa, Eisuke,Usmani, Shahid B.
, p. 597 - 600 (1998)
Coupling reaction of monoacetate 2 and aryl hard nucleophiles is realized for the first time, which consists of the lithium arylborates as hard nucleophiles and NiCl2(PPh3)2 as a catalyst. More importantly, the independent effects of t-BuCN and NaI and their synergistic function are discovered to increase regioselectivity furnishing trans 1,3-isomers 6 as the major products.
SN2 Reaction of Diarylmethyl Anions at Secondary Alkyl and Cycloalkyl Carbons
Shinohara, Riku,Ogawa, Narihito,Kawashima, Hidehisa,Wada, Kyohei,Saito, Shun,Yamazaki, Takashi,Kobayashi, Yuichi
, p. 1461 - 1478 (2019/01/25)
The substitution reaction of the diethyl allylic and propargylic phosphates with Ar2CH anions was applied to sec-alkyl phosphates to compare reactivity and stereoselectivity. However, the substitution took place on the ethyl carbon of the diethyl phosphate group. We then found that the diphenyl phosphate leaving group ((PhO)2PO2) was suited for the substitution at the sec-alkyl carbon. Enantioenriched diphenyl sec-alkyl phosphates with different substituents (Me, Et, iPr) on the vicinal position underwent the substitution reaction with almost complete inversion (>99% enantiospecificity). The substitution reactions of cyclohexyl phosphates possessing cis or trans substituents (Me and/or tBu) at the C4, C3, and C2 positions of the cyclohexane ring were also studied to observe the difference in reactivity among the cis and trans isomers. A transition-state model with the phosphate leaving group ((PhO)2PO2) in the axial position was proposed to explain the difference. This model was supported by computational calculation of the virtual substitution reaction of the structurally simpler “dimethyl” cyclohexyl phosphates (leaving group = (MeO)2PO2) with MeLi. Furthermore, the calculation unexpectedly indicated higher propensity of (PhO)2PO2 as a leaving reactivity than alkyl phosphate groups such as (MeO)2PO2 and (iPrO)2PO2.
Ligand-controlled selectivity in the desymmetrization of meso cyclopenten-1,4-diols via rhodium(I)-Catalyzed addition of arylboronic acids
Menard, Frederic,Perez, David,Sustac Roman, Daniela,Chapman, Timothy M.,Lautens, Mark
supporting information; experimental part, p. 4056 - 4068 (2010/08/07)
A highly enantioselective desymmetrization of meso cyclopent-2-ene-1,4- diethyl dicarbonates has been developed using a Rh-catalyzed asymmetric allylic substitution. Depending on the type of ligand used, each of two regioisomeric products can be obtained in good yield and excellent enantioselectivity. Under rhodium(I) catalysis, bisphosphine P-Phos ligands form trans-1,2- arylcyclopentenols as the major product, whereas Segphos ligands lead predominantly to trans-1,4-arylcyclopentenols.
Realization of anti-SN2′ selective allylation of 4-cyclopentene-1,3-diol monoester with aryl- and alkenyl-zinc reagents
Nakata, Kenya,Kiyotsuka, Yohei,Kitazume, Tomoya,Kobayashi, Yuichi
body text, p. 1345 - 1348 (2009/05/07)
(Chemical Equation Presented) Anti-SN2′ mode of allylation of the monoester of 4-cyclopentene-1,3-diol with aryl and alkenyl anions was achieved, for the first time, with the MeOCH2CO2- group as a leaving group to which R-ZnBr and CuCl (as a catalyst) were best fitted. The aryl groups successfully installed were Ph, o- and p-MeC6H 4, o-MOMOC6H4, o-MeOC6H4, and p-F-C6H4, while cis and trans alkenyl groups were attached with retention of the olefinic stereochemistries.
Aryl- and alkenyllithium preparations and copper-catalyzed reaction between the derived magnesium reagents and the monoacetate of 4-cyclopentene-1,3-diol
Nakata, Kenya,Kobayashi, Yuichi
, p. 1319 - 1322 (2007/10/03)
(Chemical Equation Presented) Aryl- and alkenyllithiums, prepared by halogen-lithium exchange with lithium, exchange with n-(or t-)BuLi, stannane-lithium exchange with n-BuLi, and direct lithiation with n-BuLi, were transformed into magnesium reagents wit
New reagent system for attaining high regio- and stereoselectivities in allylic displacement of 4-cyclopentene-1,3-diol monoacetate with aryl- and alkenylmagnesium bromides
Kobayashi, Yuichi,Nakata, Kenya,Ainai, Takayuki
, p. 183 - 186 (2007/10/03)
(Chemical Equation Presented) Low regioselectivity of RMgBr (R = aryl, alkenyl) in the CuCN-catalyzed reaction with 4-cyclopentene-1,3-diol monoacetate is improved by addition of LiCl or MgCl2 to a similar extent as previously obtained with RMg
A new reagent system for installation of an aryl group onto the monoacetate of 4-cyclopentene-1,3-diol
Ainai, Takayuki,Ito, Michiko,Kobayashi, Yuichi
, p. 3983 - 3986 (2007/10/03)
Among the three types of reagents from PhMgX (X=Br, Cl) and CuCN for phenylation of 4-cyclopentene-1,3-diol monoacetate, PhMgCl/CuCN (cat.) and Ph2Cu(CN)(MgCl)2 in THF afforded the trans-1,4-isomer efficiently (82-87% yields, 91-93% regioselectivity). Similarly, o- and p-RC6H4MgCl (R=Me, OMe, CH2=CH) in combination with CuCN furnished good to excellent reactivity and regioselectivity. As an application, a three-step synthesis of dihydromultifidene was accomplished successfully.
A new method for installation of aryl and alkenyl groups onto a cyclopentene ring and synthesis of prostaglandins
Kobayashi, Yuichi,Murugesh, Modachur G.,Nakano, Miwa,Takahisa, Eisuke,Usmani, Shahid B.,Ainai, Takayuki
, p. 7110 - 7123 (2007/10/03)
To construct a new strategy for synthesis of cyclopentanoids, the transition metal-catalyzed coupling reaction of cis 4-cyclopentene-1,3-diol monoacetate 1 with hard nucleophiles, RT-m, was investigated (eq 1 in Chart 1). Although preliminary experiments using PhZnCl, PhSnMe3, [Ph-B(Me)(OCH-(Me)CH(Me)O)]-Li+ (6a) (derived from boronate ester 4a (RT = Ph) and MeLi) in the presence of a palladium or a nickel catalyst resulted in production of unidentified compounds, enone 16, and/or ketone 17 or recovery of 1, a new borate 5a (derived from 4a and n-BuLi) in the presence of a nickel catalyst (NiCl2(PPh3)2) in THF at room temperature furnished the trans coupling products 2a (RT = Ph) and 3a (RT = Ph) in high combined yield, but with a low product ratio of 0.9:1. The ratio was improved to 13:1 by addition of t-BuCN and NaI into the reaction mixture. This is the first successful example of the reaction of 1 with a hard nucleophile, and the increase in the ratio, realized with the additives, is unprecedented. This reagent system (borate 5 (1.2-1.8 equiv), NiCl2-(PPh3)2 (5-10 mol%), t-BuCN (2-5 equiv), NaI (0.5-1 equiv), THF, room temp) was further investigated with aryl borates 5b-g and alkenyl borates 5h-n to afford 2b-n in moderate to good yields (52-89%) with practically acceptable levels of the regioselectivity (5 ～ 21:1), thus establishing the generality of the reaction (Table 2, eqs 6 and 7). Starting with the products of the coupling reaction, syntheses of the prostaglandin intermediates 13 and 14 (for 11-deoxy-PGE2 and PGA2) and Δ7-PGA1 methyl ester (15) were accomplished efficiently. During these investigations, LDA, LiCA, and LHMDS were found to be equally efficient bases for aldol reaction at the α′ (α prime) position of cyclopentenones 39, 40, and 41 (Table 3).
Regio- and stereoselective installation of alkyl groups onto cis 4-cyclopentene-1,3-diol monoacetate by using reagents derived from alkylmagnesium halides
Ito, Michiko,Murugesh, Modachur G.,Kobayashi, Yuichi
, p. 423 - 427 (2007/10/03)
Reaction of cis 4-cyclopentene-1,3-diol monoacetate with alkyl reagents derived from RMgX and CuCN furnished either trans 4-alkyl-2-cyclopenten-1-ols (1,4-isomers) or trans 2-alkyl-3-cyclopenten-1-ols (1,2-isomers) depending upon the stoichiometry of RMgX
PALLADIUM CATALYZED COUPLING OF ORGANOSTANNANES WITH VINYL EPOXIDES
Tueting, David R.,Echavarren, Antonio M.,Stille, J. K.
, p. 979 - 992 (2007/10/02)
The coupling reaction of organotin reagents with vinyl epoxides, catalyzed by palladium, takes place at ambient temperatures, regioselectively, giving predominately the 1,4-addition product.Both aryl- and vinylstannanes undergo coupling in high yields, wh
