18272-65-6Relevant 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
, 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
supporting information, 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.
Pd-Catalyzed intramolecular oxyalkynylation of alkenes with hypervalent iodine
Nicolal, Stefano,Erard, Stephane,Gonzalez, Davinla Fernandez,Waser, Jerome
supporting information; experimental part, p. 384 - 387 (2010/03/04)
(Figure presented) The first example of intramolecular oxyalkynylation of nonactivated alkenes using oxidative Pd chemistry is reported. Both phenol and aromatic or aliphatic acid derivatives could be used under operator-friendly conditions (room temperature, technical solvents, under air). The discovery of the superiority of benzlodoxolone-derlved hypervalent iodine reagent 3d as an alkyne transfer reagent further expands the rapidly increasing utility of hypervalent iodine reagents in catalysis and is expected to have important implications for other similar processes.
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.
Preparation and Reactions of Dianions from the Cresols
Bates, Robert B.,Siahaan, Teruna J.
, p. 1432 - 1434 (2007/10/02)
With n-BuLi/KO-t-Bu, protons are removed from the hydroxyl and methyl groups of cresols 5 to give dianions 6 in yields of 85percent (ortho), 95percent (meta), and 42percent (para).These dianions react with alkyl halides, Me3SiCl, Bu3SnCl, CO2, and oxidizing agents at carbon only and with dialkyl sulfates at both carbon and oxygen.Thus phenol derivatives bearing primary alkyl groups can be prepared from the corresponding methylphenols via dianions 6.
A GENERAL SYNTHESIS OF ISOTWIST-8-EN-2-ONES FROM o-(3-BUTENYL)PHENOLS
Macas, Tadas S.,Yates, Peter
, p. 147 - 150 (2007/10/02)
Wessely oxidation of o-(3-butenyl)phenols with lead tetraacetate gives 2,4-cyclohexadienone derivatives that on heating undergo intramolecular Diels-Alder reactions to give 3-acetoxyisotwist-8-en-2-ones.
Synthesis of 3-Hydroxy-2,3,4,5-tetrahydro-3-methylbenzoxepins by Ring-closure of Isoprenyl Terminal Epoxides
Baird, Kenneth J.,Grundon, Michael F.
, p. 1820 - 1825 (2007/10/02)
Terminal olefins (13), obtained from reactions of tertiary chlorides (10) with triphenylmethyl-lithium, were converted into epoxides (14); base-induced ring-closure of the latter gave 2-hydroxymethyl-2-methylchromans (15) and 3-hydroxy-2,3,4,5-tetrahydro-3-methylbenzoxepins (17).Dehydration of the tetrahydrobenzoxepin (17a) furnished dihydrobenzoxepins.
