18272-85-0Relevant academic research and scientific papers
Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids
Lu, Yanhui,Nakatsuji, Hidefumi,Okumura, Yukimasa,Yao, Lu,Ishihara, Kazuaki
supporting information, p. 6039 - 6043 (2018/05/14)
Catalytic enantioselective halocyclization of 2-alkenylphenols and enamides have been achieved through the use of chiral amidophosphate catalysts and halo-Lewis acids. Density functional theory calculations suggested that the Lewis basicity of the catalyst played an important role in the reactivity and enantioselectivity. The resulting chiral halogenated chromans can be transformed to α-Tocopherol, α-Tocotrienol, Daedalin A and Englitazone in short steps. Furthermore, a halogenated product with an unsaturated side chain may provide polycyclic adducts under radical cyclization conditions.
Development and Mechanistic Study of Quinoline-Directed Acyl C-O Bond Activation and Alkene Oxyacylation Reactions
Hoang, Giang T.,Walsh, Dylan J.,McGarry, Kathryn A.,Anderson, Constance B.,Douglas, Christopher J.
, p. 2972 - 2983 (2017/03/23)
The intramolecular addition of both an alkoxy and acyl substituent across an alkene, oxyacylation of alkenes, using rhodium catalyzed C-O bond activation of an 8-quinolinyl ester is described. Our unsuccessful attempts at intramolecular carboacylation of ketones via C-C bond activation ultimately informed our choice to pursue and develop the intramolecular oxyacylation of alkenes via quinoline-directed C-O bond activation. We provide a full account of our catalyst discovery, substrate scope, and mechanistic experiments for quinoline-directed alkene oxyacylation.
Synthesis of Chiral 1,4-Benzodioxanes and Chromans by Enantioselective Palladium-Catalyzed Alkene Aryloxyarylation Reactions
Hu, Naifu,Li, Ke,Wang, Zheng,Tang, Wenjun
, p. 5044 - 5048 (2016/04/26)
A highly enantioselective alkene aryloxyarylation led to the high-yielding formation of a series of 1,4-benzodioxanes, 1,4-benzooxazines, and chromans containing quaternary stereocenters with excellent enantioselectivity. The sterically bulky and conformationally well defined chiral monophosphorus ligand L4 or L5 was responsible for the high reactivity and enantioselectivity of these transformations. The application of this method to the synthesis of the chiral chroman backbone of α-tocopherol was demonstrated. One P is plenty: A sterically bulky and conformationally well defined chiral monophosphorus ligand enabled the highly enantioselective synthesis of a series of Oheterocycles containing a quaternary stereocenter by alkene aryloxyarylation (see scheme; X=O, C, N). The application of this transformation to the synthesis of the chiral chroman backbone of α-tocopherol is demonstrated.
Versatile friedel-crafts-type alkylation of benzene derivatives using a molybdenum complex/ortho-chloranil catalytic system
Yamamoto, Yoshihiko,Itonaga, Kouhei
experimental part, p. 10705 - 10715 (2009/12/01)
A variety of molybdenum complexes catalyze Friedel-Crafts-type alkylation reactions of benzene derivatives with alkenes and alcohols in the presence of an organic oxidant, o-chloranil. The utilization of [Mo(CO)6] and two equivalents of o-chloranil catalytically furnished the hydroarylation product of norbornene with p-xylene at 80°C, whereas [Cr(CO)6] and [W(CO)6] failed to catalyze the same reaction, thus indicating the importance of the molybdenum source. The best results were obtained when a molybdenum(II) complex [CpMoCl(CO)3] (Cp = cyclopentadienyl) was used as a precatalyst. The hydroarylation reactions also took place with styrenes, cyclohexenes, and 1 -hexene as olefin substrates. The electrophilic-substitution mechanism was proposed on the basis of the ortho/para selectivities and the Markovnikov selectivities observed for the hydroarylation products. Our hypothesis was further corroborated by the fact that in the presence of the [CpMoCl(CO)3]/o-chloranil catalytic system, secondary, benzylic, or allylic alcohols participated in the alkylation of benzenes with similar selectivities.
REGIOSELECTIVE PRENYLATION OF PHENOLS BY PALLADIUM CATALYST: SYNTHESES OF PRENYLPHENOLS AND CHROMANS
Tsukayama, Masao,Kikuchi, Makoto,Kawamura, Yasuhiko
, p. 1487 - 1490 (2007/10/02)
The palladium-catalyzed coupling reaction of iodophenols (1) with 2-methyl-3-butyn-2-ol gave alkynylphenols (2).Catalytic hydrogenation of 2 over Raney nickel and the subsequent dehydration of the resultant alkylphenols (3) gave regioselectively the desired prenylphenols (4).Dehydration of alkylphenols (3f-h) gave chromans (7).
Tandem Wessely oxidation and intramolecular Diels-Alder reactions. III. Synthesis of isotwistanes
Yates, Peter,Macas, Tadas S.
, p. 1 - 10 (2007/10/02)
Wessely oxidation of o-(3-alkenyl) phenols (5) with lead tetraacetate gives 6-acetoxy-6-(3-alkenyl)-2,4-cyclohexadien-1-ones (6), which undergo intramolecular Diels-Alder reactions to give isotwistene (hexahydro-1,5-methanoindene) derivatives (7).These, on hydrolysis followed by oxidation with periodic acid, give hexahydro-1-oxo-1H-indene-5-carboxylic acids (41, 46).Compounds 5 were prepared either by Grignard coupling of o-methoxybenzyl chloride with allyl halides followed by de-O-methylation with sodium thioethoxide or via reduction of dihydrocoumarins (18-20) to 2-chromanols (21-23) with diisobutylaluminum hydride, followed by Wittig reaction of these with ethyl (triphenylphosphoranylidene)acetate.
Chemistry of gem-Dihalocyclopropanes. XXII. Intramolecular Addition of Cyclopropylidenes to Aliphatic and Aromatic Double Bonds. A Synthesis of 2-Alkenyltropones
Skatteboel, Lars,Nilsen, Nils O.,Myhren, Finn
, p. 782 - 790 (2007/10/02)
Substituted gem-dibromocyclopropanes containing a vinylic or phenolic ether oxygen α to the cyclopropane ring undergo intramolecular cycloaddition as well as ring opening to allenes when treated with methyllithium.Cycloaddition of derivatives with a vinyl
