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.
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
supporting information, 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.
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
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.
