40053-01-8Relevant academic research and scientific papers
Sequential transhalogenation and Heck reaction for efficient access to dioxo-tetrasubstituted 2,4 E,E-dienes: synthesis of segment C1-C6 of apoptolidin
Li, Xiaojin,Zeng, Xingzhong
, p. 6839 - 6842 (2006)
Efficient access to dioxo-tetrasubstituted 2,4 E,E-dienes is developed in three steps from commercially available starting materials via sequential transhalogenation and Heck reaction, which provides potentially useful synthons for the synthesis of a tetrasubstituted conjugated diene structure in complex molecules. Thereby, segment C1-C6 of apoptolidin is synthesized.
Diastereo- and Enantioselective Cross-Couplings of Secondary Alkylcopper Reagents with 3-Halogeno-Unsaturated Carbonyl Derivatives
Kremsmair, Alexander,Skotnitzki, Juri,Knochel, Paul
supporting information, p. 11971 - 11973 (2020/09/07)
Chiral secondary alkylcopper reagents were prepared from the corresponding alkyl iodides with retention of configuration by an I/Li-exchange using tBuLi (?100 °C, 1 min) followed by a transmetalation with CuBr?P(OEt)3 (?100 °C, 20 s). These ste
Synthesis of the Conjugated Tetraene Acid Side Chain of Mycolactone e by Suzuki-Miyaura Cross-Coupling Reaction of Alkenyl Boronates
Wang, Yuan,Dai, Wei-Min
supporting information, p. 323 - 330 (2015/10/05)
The conjugated tetraene acid side chain of mycolactone E has been synthesized by the cross-coupling reaction of a trisubstituted triene bromide with a trisubstituted alkenyl boronate catalyzed by Pd(OAc)2-Aphos-Y under mildly basic conditions [K3PO4·3H2O, H2O, tetrahydrofuran (THF), 35 C, 18 h]. The conjugated tetraene product was obtained in 85 % yield without geometrical isomer(s) under the catalytic conditions. These results demonstrated that the coupling of alkenyl halides with alkenyl boronates catalyzed by Pd(OAc)2-Aphos-Y in combination with CuI-catalyzed regio- and stereoselective alkyne borylation offers an efficient synthetic tool for accessing conjugated polyene molecules.
Catalytic enantioselective nazarov cyclization: Construction of vicinal all-carbon-atom quaternary stereocenters
Jolit, Anais,Walleser, Patrick M.,Yap, Glenn P. A.,Tius, Marcus A.
, p. 6180 - 6183 (2014/06/23)
The diastereoselective asymmetric synthesis of vicinal all-carbon-atom quaternary stereocenters is a challenging problem in organic synthesis for which only few solutions have been described. A catalytic asymmetric Nazarov cyclization of fully substituted dienones that provides cyclopentenone derivatives with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers is now reported.
Synthesis of the conjugated tetraene acid side chain of mycolactone e by Suzuki-Miyaura cross-coupling reaction of alkenyl boronates
Wang, Yuan,Dai, Wei-Min
supporting information, p. 323 - 330 (2014/01/23)
The conjugated tetraene acid side chain of mycolactone E has been synthesized by the cross-coupling reaction of a trisubstituted triene bromide with a trisubstituted alkenyl boronate catalyzed by Pd(OAc)2-Aphos-Y under mildly basic conditions [K3PO4·3H 2O, H2O, tetrahydrofuran (THF), 35 °C, 18 h]. The conjugated tetraene product was obtained in 85 % yield without geometrical isomer(s) under the catalytic conditions. These results demonstrated that the coupling of alkenyl halides with alkenyl boronates catalyzed by Pd(OAc) 2-Aphos-Y in combination with CuI-catalyzed regio- and stereoselective alkyne borylation offers an efficient synthetic tool for accessing conjugated polyene molecules. Gently united: Conjugate polyenes possessing trisubstituted double bond(s) are synthesized from trisubstituted alkenyl halides and trisubstituted boronates in high yields under the catalysis of the hemilabile P,O ligand Aphos-Y and Pd(OAc)2 in the presence of K3PO4·3H2O (3 equiv.) and H2O (18 equiv.) in tetrahydrofuran (THF) at 35°C. The product is free of geometric isomers. Copyright
Highly enantioselective Rh-Catalyzed Alkenylation of imines: Synthesis of Chiral Allylic Amines via Asymmetric addition of Potassium Alkenyltrifluoroborates to N-Tosyl imines
Gopula, Balraj,Chiang, Chien-Wei,Lee, Way-Zen,Kuo, Ting-Shen,Wu, Ping-Yu,Henschke, Julian P.,Wu, Hsyueh-Liang
, p. 632 - 635 (2014/04/03)
For the first time, simple N-tosyl aryl aldimines, prepared from the condensation of tosyl amide and aromatic aldehydes, can be used as substrates in the rhodium catalyzed 1,2- addition reaction using alkenylboron nucleophiles. In the presence of 1.5 mol % of [RhCl(1e)]2, enantioselective addition of various potassium alkenyltrifluoroborates to aryl aldimines furnished the corresponding chiral allylic amines in 73-96% yield and 72->99.5% ee. Notably, this method efficiently provides the di-, tri-, and tetrasubstituted allylic N-tosyl amines with high asymmetric induction.
Gram-scale synthesis of iejimalide B
Gagnepain, Julien,Moulin, Emilie,Fuerstner, Alois
, p. 6964 - 6972 (2011/07/30)
IejimalideB (2) is the most promising member of a small family of marine polyene macrolides endowed with remarkably selective activity against human cancer cell lines. As this product, however, is hardly available from the natural sources, a detailed evaluation requires the development of an efficient and practical synthetic approach. This challenge has now been met by adapting the first total synthesis of 2 previously reported by our group to the needs of high material throughput. Redesigning the access routes to the five required building blocks in combination with a careful optimization of the fragment coupling processes provided gram amounts of this valuable compound in a sequence of no more than 16 linear steps with an overall yield of about 7 %. Key elements of the successful strategy include: i) three hydrostannylation processes of elaborate terminal alkynes with "lower order" stannyl cuprates, ii) a Brown allylation, a Noyori transfer hydrogenation, and a Marshall propargylation to set the chiral centers at C9, C17, C22 and C23, and iii) a modified Takai-Utimoto olefination for the preparation of the very labile skipped 1,4-diene flanking the ester group. The assembly process benefited from a particularly mild protocol for the Stille cross-coupling previously developed in this laboratory, which clearly outperformed the alternative Suzuki reaction in terms of yield and scalability. The 24-membered macrocyclic frame was forged by a remarkably selective ring-closing metathesis reaction (RCM), in which two out of the ten double bonds present in the cyclization precursor were selectively activated with the aid of a second-generation Grubbs catalyst. Copyright
Studies on the synthesis of apoptolidin A. 1. Synthesis of the C(1)-C(11) fragment
Handa, Masaki,Scheldt, Karl A.,Bossart, Martin,Zheng, Nan,Roush, William R.
, p. 1031 - 1035 (2008/09/18)
(Chemical Equation Presented) A synthesis of the C(1)-C(11) fragment of apoptolidin A has been accomplished by a convergent route involving the stereoselective glycosidation of 9 and the Suzuki cross-coupling reaction of bromodienoate 7 and the vinylboran
IspH protein of the deoxyxylulose phosphate pathway: Mechanistic studies with C1-deuterium-labeled substrate and fluorinated analogue
Xiao, Youli,Liu, Pinghua
supporting information; experimental part, p. 9722 - 9725 (2009/05/30)
(Chemical Equation Presented) The last step of the deoxylxylulose phosphate pathway is catalyzed by IspH to synthesize two precursors for isoprenoid biosynthesis. The lack of a primary kinetic isotope effect at C1 and enzymatic evaluation with a fluorinated analogue (see scheme) suggest that the C1-position is not involved in the IspH-catalyzed reaction. FldA = flavodoxin, Fpr = flavodoxin reductase, NADPH = nicotinamide adenine dinucleotide phosphate, PPi = P2O63-.
Enantioselective synthesis of a trans-7,8-dimethoxycalamenene
Werle, Susen,Fey, Thorsten,Neudoerfl, Joerg M.,Schmalz, Hans-Guenther
, p. 3555 - 3558 (2008/02/12)
trans-7,8-Dimethoxy-11,12-dehydrocalamenene, a projected intermediate for the total synthesis of marine serrulatane and amphilectane diterpenes, was efficiently synthesized. Starting from a styrene, asymmetric Rh-catalyzed hydroboration using a novel chiral P.P-bidentate ligand afforded an organoboron intermediate (93% ee) which was directly used for C-C bond formation (double homologation, Suzuki coupling). The 1,4-trans-disubstituted tetralin skeleton was selectively formed by a Friedel-Crafts-type catlonic cyclization under strictly aprotic conditions (Me2AlCl) to suppress a remarkable proton-catalyzed disproportionation via diastereoselective hydride transfer.
