The Experts below are selected from a list of 13131 Experts worldwide ranked by ideXlab platform
Yulin Wu - One of the best experts on this subject based on the ideXlab platform.
-
bioactivities and mechanism of spiro Enol Ether analogues against pieris rapae
Insect Science, 2004Co-Authors: Zhixiang Zhang, Hanhong Xu, Dongmei Cheng, Yulin WuAbstract:Nineteen kinds of spiro Enol Ether analogues were screened with larvae of Pieris rapae for antifeedant activity. The results showed that the antifeedant activity of compounds No.20 and No. 12 was higher than others. In non-choice test, AFC50 values within 24 h of compounds No.20 and No. 12 against 3rd instar larvae of P. rapae were 226.93 μg/mL and 370.00 μg/mL, and that in choice test against 4th larvae were 280.54 μg/mL and 398.88 μg/mL, respectively. Compd. No.20 could prolong the eggs hatch time and reduce the haemolymph content and the protein content in haemolymph of 4th instar larvae obviously. Compd. No.20 could protect tested leaves and control larvae of P. rapae effectively.
-
hydroamination of olefin in a special conjugated spiroketal Enol Ether system diastereoselective synthesis of amino containing tonghaosu analogs
Tetrahedron Letters, 2004Co-Authors: Taishan Hu, Yulin WuAbstract:Abstract Lithium amide reacted with spiroketal Enol Ether characterized tonghaosu analog at −78 °C to give the only hydroamination product 4 in a highly regio- and diastereoselective manner. At a higher temperature, −40 °C, the presence of free amine was critical for the hydroamination to take place; otherwise, rearrangement of tonghaosu analog to 2,3-dihydrofuran derivative like 6 was the only reaction.
-
acid catalysed rearrangement of a spiroketal Enol Ether an easy synthesis of chrycorin
Journal of The Chemical Society-perkin Transactions 1, 2002Co-Authors: Yikang Wu, Yulin WuAbstract:Tonghaosu, 2-[(Z)-hexa-2,4-diynylidene]-1,6-dioxaspiro[4,4]non-3-ene (1a), and its spiroketal Enol Ether analogues (1b–d and 2) were efficiently converted into interesting cyclopentenone derived oxabicyclic compounds. By applying this reaction protocol the natural product chrycorin was easily synthesized in its racemic form. A reaction mechanism for this is proposed.
-
convenient syntheses of tonghaosu and two thiophene substituted spiroketal Enol Ether natural products
Tetrahedron Letters, 1996Co-Authors: Wenlian Wu, Bin Ye, Rong Zhou, Yulin WuAbstract:A convenient synthetic method of spiroketal Enol Ether by dehydration-spiroketalization reaction from furan intermediate and its application for the syntheses of three natural products, tonghaosu (1) and 2, 3, was reported.
Atsushi Nishida - One of the best experts on this subject based on the ideXlab platform.
-
abnormal ito saegusa oxidation of tips Enol Ether assisted by a hydroxy group on a side chain
ChemInform, 2011Co-Authors: Shiharu Hiraoka, Shinji Harada, Atsushi NishidaAbstract:Although Ito-Saegusa oxidation gives defined α,β-unsaturated ketones from silyl Enol Ether of ketones, controlled by the position of the sp2 carbon of the silyl Enol Ether, the formation of a regioisomeric product that is oxidized abnormally is observed.
-
abnormal ito saegusa oxidation of tips Enol Ether assisted by a hydroxy group on a side chain
Tetrahedron Letters, 2011Co-Authors: Shiharu Hiraoka, Shinji Harada, Atsushi NishidaAbstract:Abstract Although Ito–Saegusa oxidation gives defined α,β-unsaturated ketones from silyl Enol Ether of ketones controlled by the position of the sp 2 carbon of the silyl Enol Ether, the formation of a regioisomeric product that was oxidized abnormally was observed. The structural requirements for the substrates, the conditions, and a plausible mechanism are presented.
-
Synthesis of substituted 1,2-dihydroquinolines and quinolines using ene–ene metathesis and ene–Enol Ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol Ether metathesis. We also report the first example of Enol silyl Ether–ene metathesis to produce cyclic Enol silyl Ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
-
synthesis of substituted 1 2 dihydroquinolines and quinolines using ene ene metathesis and ene Enol Ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol Ether metathesis. We also report the first example of Enol silyl Ether–ene metathesis to produce cyclic Enol silyl Ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
Mitsuhiro Arisawa - One of the best experts on this subject based on the ideXlab platform.
-
cycloisomerization between aryl Enol Ether and silylalkynes under ruthenium hydride catalysis synthesis of 2 3 disubstituted benzofurans
Organic Letters, 2017Co-Authors: Shohei Ohno, Kohei Takamoto, Hiromichi Fujioka, Mitsuhiro ArisawaAbstract:Metal-catalyzed cycloisomerization reactions of 1,n-enynes have become conceptually and chemically attractive processes in the search for atom economy, which is a key subject of current research. However, metal-catalyzed cycloisomerization between aryl Enol Ether and silylalkynes has not been developed. The ruthenium hydride complex catalyzed cycloisomerization between aryl Enol Ether and silylalkynes is reported to give benzofurans having useful functional groups, vinyl and trimethylsilylmethyl, on the 2- and 3-positions, respectively.
-
Synthesis of substituted 1,2-dihydroquinolines and quinolines using ene–ene metathesis and ene–Enol Ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol Ether metathesis. We also report the first example of Enol silyl Ether–ene metathesis to produce cyclic Enol silyl Ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
-
synthesis of substituted 1 2 dihydroquinolines and quinolines using ene ene metathesis and ene Enol Ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol Ether metathesis. We also report the first example of Enol silyl Ether–ene metathesis to produce cyclic Enol silyl Ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
Shunichi Hashimoto - One of the best experts on this subject based on the ideXlab platform.
-
catalytic asymmetric synthesis of ritodrine hydrochloride via silyl Enol Ether amination using dirhodium ii tetrakis tetrafluorophthaloyl s tert leucinate
Heterocycles, 2008Co-Authors: Shunichi Hashimoto, Masahiko Tanaka, Seiichi Nakamura, Masahiro AnadaAbstract:- A catalytic asymmetric synthesis of (-)-ritodrine hydrochloride was achieved, incorporating an enantioselective amination of (Z)-silyl Enol Ether derived from 4-benzyloxypropiophenone with [(2-nitrophenylsulfonyl)imino]-phenyliodinane (NsN=IPh) and a chelation-controlled reduction of the ketone carbonyl group with Zn(BH 4 ) 2 as the key steps. The use of dirhodium(II) tetrakis[tetrafluorophthaloyl-(S)-tert-leucinate] as a catalyst produced the targeted α-amino ketone in 94% yield with 91% ee.
-
Chiral base-catalyzed aldol reaction of trimethoxysilyl Enol Ethers: effect of water as an additive on stereoselectivities
Tetrahedron, 2006Co-Authors: Yuya Orito, Tadao Ishizuka, Shunichi Hashimoto, Makoto NakajimaAbstract:An aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate is described. The aldol reaction of trimethoxysilyl Enol Ether derived from cyclohexanone under anhydrous conditions predominantly afforded the anti-aldol adduct with moderate enantioselectivity, whereas the reaction under aqueous conditions predominantly resulted in the syn-adduct and the enantioselectivity of the syn-adduct was considerably improved. The best enantioselectivity was obtained in the reaction of trimethoxysilyl Enol Ether derived from 1-indanone with cyclohexanecarboxaldehyde (97% ee (syn)). This is the first example of an aldol reaction of trimethoxysilyl Enol Ether catalyzed by a chiral base.
-
enantioselective aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate
Organic Letters, 2004Co-Authors: Makoto Nakajima, Yuya Orito, Tadao Ishizuka, Shunichi HashimotoAbstract:An aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate, in which water serves as an additive and plays a pivotal role in stereoselectivities, was developed. This is the first example of an aldol reaction of trimethoxysilyl Enol Ether catalyzed by a chiral base.
Makoto Nakajima - One of the best experts on this subject based on the ideXlab platform.
-
Chiral base-catalyzed aldol reaction of trimethoxysilyl Enol Ethers: effect of water as an additive on stereoselectivities
Tetrahedron, 2006Co-Authors: Yuya Orito, Tadao Ishizuka, Shunichi Hashimoto, Makoto NakajimaAbstract:An aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate is described. The aldol reaction of trimethoxysilyl Enol Ether derived from cyclohexanone under anhydrous conditions predominantly afforded the anti-aldol adduct with moderate enantioselectivity, whereas the reaction under aqueous conditions predominantly resulted in the syn-adduct and the enantioselectivity of the syn-adduct was considerably improved. The best enantioselectivity was obtained in the reaction of trimethoxysilyl Enol Ether derived from 1-indanone with cyclohexanecarboxaldehyde (97% ee (syn)). This is the first example of an aldol reaction of trimethoxysilyl Enol Ether catalyzed by a chiral base.
-
enantioselective aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate
Organic Letters, 2004Co-Authors: Makoto Nakajima, Yuya Orito, Tadao Ishizuka, Shunichi HashimotoAbstract:An aldol reaction of trimethoxysilyl Enol Ether catalyzed by lithium binaphtholate, in which water serves as an additive and plays a pivotal role in stereoselectivities, was developed. This is the first example of an aldol reaction of trimethoxysilyl Enol Ether catalyzed by a chiral base.