- Copper-catalyzed regiodivergent silacarboxylation of allenes with carbon dioxide and a silylborane
-
A regiodivergent silacarboxylation of allenes under a CO2 atmosphere with PhMe2Si-B(pin) as a silicon source in the presence of a copper catalyst at 70 °C has been developed. The regioselectivity of the reaction is successfully rever
- Tani, Yosuke,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
-
-
Read Online
- Rapid Access to Nitrogenous Heterobicycles via RhIII-Catalyzed Isomerization from Alkynes to Allenes
-
We show that N-alkynylnitrones are efficiently converted to nitrogenous heterobicyclic compounds with a nitrogen atom at the bridgehead position by using a RhIII-catalyst. Our mechanistic studies suggest that the reaction proceeds via an allene
- Nakamura, Itaru,Takeda, Keisuke,Sato, Yoshinori,Terada, Masahiro
-
-
Read Online
- Directed Cobalt-Catalyzed anti-Markovnikov Hydroalkylation of Unactivated Alkenes Enabled by "co-H" Catalysis
-
The earth-abundant cobalt-catalyzed anti-Markovnikov hydroalkylation of unactivated alkenes with oxime esters was achieved by introducing an 8-aminoquinoline directing group on the alkenes. The catalytic system, consisting of commercially available Co(acac)3 and PhMeSiH2, enables the construction of unfunctionalized C(sp3)-C(sp3) bonds and features exclusive anti-Markovnikov selectivity, good functional group tolerance, and the avoidance of an extra ligand, oxidant, or base. Mechanistic insight into this new catalytic system indicates the involvement of both alkyl radical and cobalt hydride intermediates.
- Yang, Dandan,Huang, Hai,Li, Meng-Hui,Si, Xiao-Ju,Zhang, He,Niu, Jun-Long,Song, Mao-Ping
-
supporting information
p. 4333 - 4338
(2020/06/04)
-
- Bioinspired Divergent Oxidative Cyclizations of Geissoschizine: Total Synthesis of (–)-17-nor-Excelsinidine, (+)-16-epi-Pleiocarpamine, (+)-16-Hydroxymethyl-Pleiocarpamine and (+)-Taberdivarine H
-
We report a full account of our efforts towards bioinspired oxidative cyclizations of geissochizine and analogs to mimic the biosynthesis of the mavacuran, akuammilan, and excelsinidine groups of monoterpene indole alkaloids. The construction of the A,B,C,D ring system of geissoschizine was first achieved by merging two known syntheses of this alkaloid. Modified Ma's oxidative conditions (KHMDS/I2) applied directly to geissoschizine induced formation of the N4–C16 bond encountered in the excelsinidines core. Identical conditions applied to C16-dimethylmalonate-containing N4-quaternized substrates ended in the formation of the mavacurans core (N1–C16 bond). With this unified oxidative cyclization strategy: (–)-17-nor-excelsinidine, (+)-16-epi-pleiocarpamine, (+)-16-hydroxymethyl-pleiocarpamine, 16-formyl-pleiocarpamine and (+)-taberdivarine H were synthetized. We also report a shortened total synthesis of 16-epi-pleiocarpamine compared to our preliminary communication from a C16-monoester analog. Alternatively, 17-nor-excelsinidine was synthesized via an intramolecular nucleophilic substitution of a 7-membered ring α-chlorolactam prepared from 16-desformyl-geissoschizine.
- Jarret, Maxime,Tap, Aurélien,Turpin, Victor,Denizot, Natacha,Kouklovsky, Cyrille,Poupon, Erwan,Evanno, Laurent,Vincent, Guillaume
-
supporting information
p. 6340 - 6351
(2020/09/07)
-
- Construction of All-Carbon Chiral Quaternary Centers through CuI-Catalyzed Enantioselective Reductive Hydroxymethylation of 1,1-Disubstituted Allenes with CO2
-
A catalytic enantioselective construction of all-carbon chiral quaternary centers through reductive hydroxymethylation of 1,1-disubstituted allenes with CO2 has been developed. In the presence of a copper/Mandyphos catalyst, CO2 is t
- Qiu, Jia,Gao, Shen,Li, Chaopeng,Zhang, Lei,Wang, Zheng,Wang, Xiaoming,Ding, Kuiling
-
supporting information
p. 13874 - 13878
(2019/11/11)
-
- Pd(ii)-SDP-catalyzed enantioselective 5-exo-dig cyclization of γ-alkynoic acids: Application to the synthesis of functionalized dihydofuran-2(3H)-ones containing a chiral quaternary carbon center
-
The Pd(ii)-SDP-catalyzed first enantioselective intramolecular cyclization of α,α-disubstituted γ-alkynoic acids is described. This 5-exo-dig cyclization afforded dihydrofuran-2(3H)-ones bearing a chiral quaternary carbon center in excellent yields with e
- Sridharan, Vellaisamy,Fan, Lulu,Takizawa, Shinobu,Suzuki, Takeyuki,Sasai, Hiroaki
-
supporting information
p. 5936 - 5943
(2013/09/12)
-
- Fused ring aziridines as a facile entry into triazole fused tricyclic and bicyclic heterocycles
-
The intramolecular dipolar cycloaddition of an azide with an alkyne has provided a useful entry into triazole fused tricyclic heterocycles containing both the triazole ring and the oxazolidin-2-one ring system. The requisite azido-alkynes have been prepared via a two-step sequence from fused ring aziridines. A series of 6-12 membered rings containing both the oxazolidinone and triazole rings have been prepared. These ring systems have been designed as conformationally restrained analogs of RNA-binding oxazolidinones. The Royal Society of Chemistry 2012.
- Fang, Fang,Vogel, Megan,Hines, Jennifer V.,Bergmeier, Stephen C.
-
scheme or table
p. 3080 - 3091
(2012/05/07)
-
- 2-(3-AMINOPIPERIDIN-1-YL)-[1,2,4]TRIAZOLO[1,5-C]PYRIMIDINE-5,7(3H,6H)-DIONE DERIVATES AS DIPEPTIDYL PEPTIDASE IV(DPP-IV) INHIBITORS
-
Provided are 2-(3-aminopiperidin-1-yl)-[1,2,4]triazolo[1,5-c]pyrimidine-5,7(3H,6H)-dione derivates as dipeptidyl peptidase IV (DPP-IV) inhibitors, pharmaceutical compositions thereof, and methods of use thereof
- -
-
Page/Page column 47
(2012/07/14)
-
- CERTAIN DIPEPTIDYL PEPTIDASE INHIBITORS
-
Provided are certain dipeptidyl peptidase inhibitors, pharmaceutical compositions thereof, and methods of use therefor.
- -
-
Page/Page column 47
(2012/07/14)
-
- Synthetic applications of the nickel-catalyzed cyclization of alkynes combined with addition reactions in a domino process
-
Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel-catalyzed domino cyclization-condensation process. This reaction, which does not require the preparation of any other organometallic reagent, proceeds only by exo-dig cyclization. This convenient and mild method constitutes a one-pot synthesis of substituted dihydrobenzofurans, chromans, isochromans, indoles, or indanes. Theses valuable products are generally obtained in good yields and high stereoselectivity. They are shown to be useful synthons for rapid access to functionalized polycyclic skeletons. Yes nickel can! Carbonickelation of alkynes and functionalization of the resulting vinylnickel moiety occurs efficiently. Overall, a domino cyclization-condensation process propagated by substoichiometric nickel catalysis takes place (see scheme). This one-pot synthesis provides substituted polyheterocyclic compounds in good yields and high stereoselectivity.
- Durandetti, Muriel,Hardou, Lucie,Lhermet, Rudy,Rouen, Mathieu,Maddaluno, Jacques
-
supporting information; experimental part
p. 12773 - 12783
(2011/12/04)
-
- Iron-catalyzed, hydrogen-mediated reductive cyclization of 1,6-enynes and diynes: Evidence for bis(imino)pyridine ligand participation
-
(Chemical Equation Presented) The bis(imino)pyridine iron dinitrogen complex (iPrPDI)Fe(N2)2 catalyzes the hydrogen-mediated reductive cyclization of enynes and diynes with turnover frequencies comparable to those of established precious metal catalysts. Amino, oxygenated, and carbon-based substrates are readily cyclized to the corresponding hetero- and carbocycles with 5 mol % iron and 4 atm H2 at 23°C. Stoichiometric reactions between selected substrates and the iron compound under a N2 atmosphere established transfer dehydrogenation from an isopropyl aryl substituent to either the enyne or diyne substrate. In situ monitoring of the catalytic reaction by 1H NMR spectroscopy coupled with deuterium labeling experiments established rapid cyclization followed by turnoverlimiting hydrogenation. Copyright
- Sylvester, Kevin T.,Chirik, Paul J.
-
supporting information; experimental part
p. 8772 - 8774
(2009/12/04)
-
- Aza cope rearrangement of propargyl enammonium cations catalyzed by a self-assembled "nanozyme"
-
The tetrahedral assembly [Ga4L6]12- [L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga4L6]12- assembly, rate accelerations by factors of up to 184 compared with the background reaction rate were observed. After rearrangement, the product iminium ion is released into solution and hydrolyzed, allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a decrease in the entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics: the rate data obeyed the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a nonreactive guest was demonstrated.
- Hastings, Courtney J.,Fiedler, Dorothea,Bergman, Robert G.,Raymond, Kenneth N.
-
supporting information; experimental part
p. 10977 - 10983
(2009/02/05)
-
- Reduction of propargylic sulfones to (Z)-allylic sulfones using zinc and ammonium chloride
-
Propargylic sulfones can be cis-hydrogenated using commercial zinc powder and ammonium chloride in THF-water at room temperature, the major products being the corresponding (Z)-allylic sulfones. Other reducible groups (alkene, benzyloxy) are not affected. Allenylsulfones are implicated in one of the possible reaction pathways.
- Sheldrake, Helen M.,Wallace, Timothy W.
-
p. 4407 - 4411
(2008/02/03)
-
- Nematic tolanes and acetylenes
-
The first liquid crystals incorporating a non-conjugated carbon-carbon triple bond in the terminal chain to exhibit a nematic phase above the melting point are reported. A variety of compounds incorporating a carbon-carbon triple bond in the terminal chain or between two phenyl rings have been synthesised as part of an investigation of the effects of the shape, conformation and rigidity of the terminal chains of liquid crystals on their mesophase behaviour. A series of related tolanes incorporating an alkenyloxy chain with an additional carbon-carbon double bond or a simple alkoxy chain as a terminal substituent also were prepared for comparison purposes.
- Skelton, Graham W.,Dong, Dewen,Tuffin, Rachel P.,Kelly, Stephen M.
-
p. 450 - 457
(2007/10/03)
-
- Allenylmethylsilanes as nucleophiles in N-acyliminium ion chemistry
-
(matrix presented) Treatment of a variety of N-acyliminium ion precursors with 2,3-butadienyl(trimethyl)silane and related allenes in the presence of BF3·OEt2 provides good yields of N-protected 2-(aminomethyl)-substituted 1,3-dienes
- Mentink, Gertjan,Van Maarseveen, Jan H.,Hiemstra, Henk
-
p. 3497 - 3500
(2007/10/03)
-
- Preparation of 2-iodo-1,3-butadienes from 1-trimethylsilyl-2,3- butadienes and their functionalizations
-
Successive treatment of 1-trimethylsilyl-2.3-butadienes with iodine and tetra-n-butylammonium fluoride in the same flask affords 2-iodo-1.3- butadienes in good yields and their palladium-catalyzed carbonylation and alkynylation allows introduction of este
- Nishiyama, Takashi,Esumi, Tomoyuki,Iwabuchi, Yoshiharu,Irie, Hiroshi,Hatakeyama, Susumi
-
-
- Synthesis of Enantiomerically Pure Unsaturated α-Amino Acids Using Serine-Derived Zinc/Copper Reagents
-
Treatment of the serine-derived organozinc reagent 2, in benzene/dimethylacetamide, with a THF solution of CuCN*2LiCl gives rise to a zinc/copper reagent 6 which reacts directly with allylic halides and tosylates to give the corresponding enantiomerically pure substitution products 9 in 32-65percent yield (11 examples).The reaction proceeds by formal SN2' displacement of the leaving group.Reaction with propargyl halides gives the corresponding terminal allene 12a.The zinc reagent 2 may also be prepared directly from protected iodoalanine 1 in THF by the Knochel method.Reaction with propargylic tosylates as electrophiles gives rise to the corresponding protected terminal allenic amino acids in 51-81percent yield (four examples); use of enantiomerically enriched propargylic tosylates results in the formation of diastereoisomerically enriched allenic products.Reactions of the zinc/copper reagent 6 with a range of representative electrophiles is explored; use of relatively reactive electrophiles is necessary to obtain satisfactory yields.Finally, the possibility of using the serine-derived iodide 20, in which the carboxylic acid is protected as a methyl ester, is established.This reagent offers advantages over the corresponding benzyl ester protected reagent 6 for the synthesis of unsaturated amino acids.
- Dunn, Michael J.,Jackson, Richard F. W.,Pietruszka, Joerg,Turner, Debra
-
p. 2210 - 2215
(2007/10/02)
-
- Stereocontrolled Construction of Substituted Pyrrolidines based on Intramolecular Protodesilylation Reaction. Enantiospecific Synthesis of (-)-Kainic Acid and (+)-Allokainic Acid from L-Serine
-
Novel stereocontrolled enantiospecific syntheses of (-)-kainic acid and (+)-allokainic acid have been achieved starting from L-serine via two modes of C-2 and C-3 side chain-directed intramolecular protodesilylations of 4-(trimethylsilylmethyl)ethylidenepyrrolidines.
- Hatakeyama, Susumi,Sugawara, Kazutoshi,Takano, Seiichi
-
p. 125 - 127
(2007/10/02)
-