194869-04-0Relevant articles and documents
A facile pathway to enantiomerically enriched 3-hydroxy-2-oxindoles: Asymmetric intramolecular arylation of α-keto amides catalyzed by a palladium-DifluorPhos complex
Yin, Liang,Kanai, Motomu,Shibasaki, Masakatsu
supporting information; scheme or table, p. 7620 - 7623 (2011/09/30)
Less metal wastes: The first catalytic, enantioselective intramolecular aryl-transfer reaction of aryl triflates to ketones has been developed (see scheme; R1=R2=aromatic and aliphatic). This method features overall practicality, inc
Catalytic asymmetric synthesis of R207910
Saga, Yutaka,Motoki, Rie,Makino, Sae,Shimizu, Yohei,Kanai, Motomu,Shibasaki, Masakatsu
supporting information; experimental part, p. 7905 - 7907 (2010/08/05)
The first asymmetric synthesis of a very promising antituberculosis drug candidate, R207910, was achieved by developing two novel catalytic transformations; a catalytic enantioselective proton migration and a catalytic diastereoselective allylation of an intermediate α-chiral ketone. Using 2.5 mol % of a Y-catalyst derived from Y(HMDS)3 and the new chiral ligand 9, 1.25 mol % of p-methoxypyridine N-oxide (MEPO), and 0.5 mol % of Bu4NCl, α-chiral ketone 3 was produced from enone 4 with 88% ee. This reaction proceeded through a catalytic chiral Y-dienolate generation via deprotonation at the γ-position of 4, followed by regio- and enantioselective protonation at the α-position of the resulting dienolate. Preliminary mechanistic studies suggested that a Y: 9: MEPO = 2: 3: 1 ternary complex was the active catalyst. Bu4NCl markedly accelerated the reaction without affecting enantioselectivity. Enantiomerically pure 3 was obtained through a single recrystallization. The second key catalytic allylation of ketone 3 was promoted by CuF·3PPh3·2EtOH (10 mol %) in the presence of KOtBu (15 mol %), ZnCl2 (1 equiv), and Bu4PBF4 (1 equiv), giving the desired diastereomer 2 in quantitative yield with a 14: 1 ratio without any epimerization at the α-stereocenter. It is noteworthy that conventional organometallic addition reactions did not produce the desired products due to the high steric demand and a fairly acidic α-proton in substrate ketone 3. This first catalytic asymmetric synthesis of R207910 includes 12 longest linear steps from commercially available compounds with an overall yield of 5%.
Chiral relay effect: 4-substituted 1,3-benzoxazol-2-(3H)-ones as achiral templates for enantioselective Diels-Alder reactions
Quaranta, Laura,Corminboeuf, Olivier,Renaud, Philippe
, p. 39 - 41 (2007/10/03)
(matrix presented) A new strategy to control the enantioselectivity of Lewis acid catalyzed reactions has been investigated. The use of N-acryloyl-1,3-benzoxazol-2-(3H)-ones substituted at position 4 leads to the formation of diastereomeric complexes as a
A mild deprotection of trichloroethyl carbamates using indium metal
Mineno, Tomoko,Choi, Seoung-Ryoung,Avery, Mitchell A.
, p. 883 - 886 (2007/10/03)
The trichloroethoxycarbonyl moiety was efficiently removed from carbamates to furnish the corresponding amines using indium metal in good to excellent yields.
General and facile synthesis of indoles with oxygen-bearing substituents at the benzene moiety
Kondo, Yoshinori,Kojima, Satoshi,Sakamoto, Takao
, p. 6507 - 6511 (2007/10/03)
Indoles with oxygen-bearing substituents such as a methoxy or (triisopropylsilyl)oxy group at all of the positions of the benzene moiety were synthesized by cyclization of tert-butyl methoxy(or (triisopropylsilyl)oxy)-2-((trimethylsilyl)ethynyl)phenyl)carbamates with potassium tert-butoxide in tert-butyl alcohol. The (ethynylphenyl)carbamates were synthesized by the palladium-catalyzed reaction of (trimethylsilyl)acetylene and the corresponding (iodophenyl)carbamates, which were selectively synthesized by directed lithiation of the phenylcarbamates and subsequent iodination.