708-83-8Relevant academic research and scientific papers
Divergent Synthetic Access to E- and Z-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens
Ashida, Yuichiro,Honda, Atsushi,Sato, Yuka,Nakatsuji, Hidefumi,Tanabe, Yoo
, p. 73 - 89 (2017/02/10)
A highly substrate-general synthesis of all-carbon-substituted E- and Z-stereodefined olefins is performed. The method comprises two sets of parallel and stereocomplementary preparations of (E)- and (Z)-α,β-unsaturated esters involving two robust and distinctive reactions: 1) stereocomplementary enol tosylations using readily available TsCl/diamine/(LiCl) base reagents, and 2) stereoretentive Negishi cross-coupling using the catalysts [Pd(dppe)Cl2] (for E) and [Pd(dppb)Cl2] (for Z). The present parallel approach is categorized as both type I (convergent approach: 16 examples, 56–87 % yield) and type II (divergent approach: 18 examples, 70–95 % yield). The obtained (E)- and (Z)-α,β-unsaturated ester scaffolds are successfully transformed into various E- and Z-stereodefined known and novel olefins (8×2 derivatization arrays). As a demonstration, application to the parallel synthesis of both (E)- and (Z)-tamoxifens, a representative motif of all-carbon-substituted olefins, is accomplished in a total of eight steps with an overall yield of 58 % (average 93 %) and 57 % (average 93 %), respectively.
The Development of a Stereoselective Method for the Synthesis of Tetrasubstituted Derivatives of α,β-Unsaturated Carboxylic Acids
Rzymkowski, Jan,Pi?tek, Anna
, p. 665 - 673 (2016/09/21)
Alkenes possessing four different carbon-linked substituents are the main structural motif of many biologically active compounds. The derivatives of (2E)-3-(3-methoxyphenyl)-2-methylpent-2-enoic acid ((E)-2c) are suitable precursors for the synthesis of Tapentadol, a novel centrally acting analgesic. It was found that the Ni-carbometallation reaction of disubstituted alkyne 8 with CO2and an Et2Zn allows for efficient and practical preparation of (E)-2c as a single (E)-regioisomer in 89% of isolated yield. The influence of the size of the aliphatic substituent of alkyne and the steric hindrance of the organozinc reagent on stereochemical course of the carbometallation reaction was evaluated. Finally, air-stable Ni(dme)Cl2was proposed as an alternative to widely used Ni(cod)2catalyst.
Catalytic enantioselective nazarov cyclization: Construction of vicinal all-carbon-atom quaternary stereocenters
Jolit, Anais,Walleser, Patrick M.,Yap, Glenn P. A.,Tius, Marcus A.
supporting information, 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.
Generation of ynolates via reductive lithiation using flow microreactors
Umezu, Satoshi,Yoshiiwa, Toshiya,Tokeshi, Manabu,Shindo, Mitsuru
, p. 1822 - 1825 (2014/03/21)
A new method has been developed for the generation and subsequent reaction of ynolates in a micro flow reactor system. This new procedure allowed for ynolates to be prepared at 0 C or ambient temperature within 1 min via a reductive lithiation reaction, whereas the corresponding batch processes generally require low temperature control and extended reaction times of up to 1 h. The resulting ynolates were applied to the olefination of carbonyl compounds, with the reactions reaching completion in a much shorter reaction time in the continuous flow reactor than the batch reactor. These results highlight the practical utility of the ynolate reaction, and represent the first reported example of the use of lithium naphthalenide in a flow microreactor, which would contribute to progress of the flash chemistry.
Diastereospecific nazarov cyclization of fully substituted dienones: Generation of vicinal all-carbon-atom quaternary stereocenters
Jolit, Anais,Vazquez-Rodriguez, Saleta,Yap, Glenn P. A.,Tius, Marcus A.
, p. 11102 - 11105 (2013/10/22)
No vacancy: Fully substituted dienones that are highly polarized by a vinylogous carbonate group were found to undergo a remarkably rapid and diastereospecific Nazarov cyclization that led to cyclopentenones with vicinal all-carbon-atom quaternary centers (see example; SEM=2-(trimethylsilyl) ethoxymethyl, Tf=trifluoromethanesulfonyl). Copyright
Key structural features of cis-cinnamic acid as an allelochemical
Abe, Masato,Nishikawa, Keisuke,Okuda, Katsuhiro,Shindo, Mitsuru,Fukuda, Hiroshi,Nakanishi, Kazunari,Tazawa, Yuta,Taniguchi, Tomoya,Park, So-Young,Hiradate, Syuntaro,Fujii, Yoshiharu
, p. 56 - 67,12 (2012/12/12)
1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
Rhodium-catalyzed and zinc(II)-triflate-promoted asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones
Calvin, Joel R.,Frederick, Michael O.,Laird, Dana L. T.,Remacle, Jacob R.,May, Scott A.
, p. 1038 - 1041 (2012/04/10)
The asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones has been accomplished using an in situ formed rhodium-Josiphos catalyst. The reaction is enhanced by addition of catalytic zinc(II) triflate, which significantly improves turnover fr
Highly efficient enantioselective synthesis of optically active carboxylic acids by Ru(OCOCH3)2[(S)-H8-BINAP]
Uemura, Toshitsugi,Zhang, Xiaoyoung,Matsumura, Kazuhiko,Sayo, Noboru,Kumobayashi, Hidenori,Ohta, Tetsuo,Nozaki, Kyoko,Takaya, Hidemasa
, p. 5510 - 5516 (2007/10/03)
In the presence of a catalytic amount of Ru(OCOCH3)2[(S)-H8-BINAP] [H8-BINAP = 2,2′-bis-(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′- octahydro-1,1′-binaphthyl], the asymmetric hydrogenation of α,β- and β,γ-unsaturated carboxylic acids afforded the corresponding saturated carboxylic acids in higher enantiomeric excesses and at faster reaction rates than those using the Ru(OCOCH3)2[(R)-BINAP] catalyst [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]. The hydrogenation of (E)-2-alkyl-2-alkenoic acids by the H8-BINAP catalyst system produced saturated acids in 95-97% ee. 2-Methylcinnamic acid was treated with H8-BINAP-Ru(II) complex as a catalyst to yield a hydrogenated product in much higher ee than that produced by BINAP-Ru(II) (89 and 30% ee, respectively). This homogeneous catalysis using H8-BINAP-Ru(II) established a promising synthetic route to (S)-ibuprofen in up to 97% ee. Asymmetric hydrogenation of β-disubstituted acrylic acids also proceeded smoothly with good enantioselectivities (70-93% ee). In addition, the hydrogenation of trisubstituted acrylic acids (up to 88% ee) was investigated. Hydrogen pressure effect on the sense and level of enantioselection was shown to be substrate dependent. The difference between the H8-BINAP- and BINAP-Ru(II) complexes was also discussed.
OXANICKELACYCLOPENTEN-DERIVATE, EIN NEUER TYP VIELSEITIG VERWENDBARER SYNTHONE
Hoberg, Heinz,Schaefer, Dietmar,Burkhart, Georg
, p. C21 - C24 (2007/10/02)
Oxanickelacyclopentene derivatives (I), which can easily be prepared from carbon dioxide, alkynes and nickel(0) compounds, are shown to be versatile synthones.Some representative examples are given.
SYNTHESIS, MOLECULAR PROPERTIES AND PHARMACOLOGICAL ACTIVITY OF SOME p-SUBSTITUTED (E)- AND (Z)-α,β-DIMETHYLCINNAMIC ACIDS
Balsamo, Aldo,Crotti, Paolo,Macchia, Bruno,Macchia, Franco,Martinelli, Adriano,et al.
, p. 327 - 332 (2007/10/02)
A series of p-substituted (E)- and (Z)-α,β-dimethylcinnamic acids has been prepared and pharmacologically tested.The configurations of the acids prepared were determined from their NMR spectra.The UV spectra and the acid dissociation constants are reported.The collected data show that an extensive conjugation between the aryl and carboxy groups via the double bond does not exist, due to the steric hindrance of the α,β-dimethyl substitution on the cinnamic system.
