Agostic interactions in alkyl derivatives of sterically hindered tris(pyrazolyl)borate complexes of niobium

2009 ◽  
Vol 253 (5-6) ◽  
pp. 635-646 ◽  
Author(s):  
Michel Etienne ◽  
John E. McGrady ◽  
Feliu Maseras
Author(s):  
G. A. Razuvaev ◽  
G. A. Abakumov ◽  
E. S. Klimov ◽  
E. N. Gladyshev ◽  
P. Ya. Bayushkin

1984 ◽  
Vol 49 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Věra Přikrylová ◽  
Petr Sedmera ◽  
Josef V. Jizba ◽  
Jindřich Vokoun ◽  
Helena Lipavská ◽  
...  

Reaction of daunomycinone (I) with alcohols and p-toluenesulfonic acid produces a mixture (~3 : 1) of its (7S)- and (7R)-O-alkyl derivatives II-IX. According to the 1H NMR evidence, the alicyclic ring exists in the 9H8 conformation in (7R)-O-alkyl derivatives, on the contrary to (7S)-epimers and 7-epi-daunomycinone that adopt the 8H9 conformation.


Author(s):  
D.M. Beltukova ◽  
V.P. Belik ◽  
Y.N. Antonenko ◽  
A.A. Bogdanov ◽  
G.A. Korshunova ◽  
...  

1990 ◽  
Vol 9 (1) ◽  
pp. 260-265 ◽  
Author(s):  
Rocco A. Paciello ◽  
Juan M. Manriquez ◽  
John E. Bercaw

1933 ◽  
Vol 55 (11) ◽  
pp. 4657-4662 ◽  
Author(s):  
Emil Klarmann ◽  
Louis W. Gates ◽  
Vladimir A. Shternov ◽  
Philip H. Cox

Author(s):  
J. A. Barltrop ◽  
R. M. Acheson ◽  
P. G. Philpott ◽  
K. E. MacPhee ◽  
J. S. Hunt

2006 ◽  
Vol 84 (10) ◽  
pp. 1250-1253 ◽  
Author(s):  
Mee-Kyung Chung ◽  
Paul Fancy ◽  
Jeffrey M Stryker

The direct synthesis of sterically hindered, partially etherified derivatives of tetrakis(2-hydroxyphenyl)ethene is reported by using the McMurry reductive olefination reaction on a range of differentially substituted 2,2′-dialkoxy benzophenone substrates. Three orthogonal protection strategies are demonstrated, incorporating β-silylethyl, 3-butenyl, and tert-butyl protecting groups, respectively, into the starting benzophenones. The latter proved most efficient, with both the McMurry coupling and deprotection steps occurring concomitantly under the McMurry conditions to directly yield the desired bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene as a 1:1 mixture of E- and Z-diastereoisomers.Key words: preorganized polyaryloxide ligands, McMurry olefination, titanium trichloride, supramolecular chemistry, tetrakis(2-hydroxyphenyl)ethene, 2,2′-disubstituted benzophenone.


1966 ◽  
Vol 44 (11) ◽  
pp. 1247-1258 ◽  
Author(s):  
Raj Nandan Prasad ◽  
Karin Tietje

The formation of 3-oxo-3,4-dihydro-2H-1,4-benzothiazine (IIIa) by cyclization of alkyl 2-haloacetamidophenyl sulfides (I) was investigated; it is proposed that the reaction proceeds via a six-membered sulfonium halide. The preparation of 4-alkyl derivatives of IIIa and of 4-alkyl and 4-acyl derivatives of its reduction product 3,4-dihydro-2H-1,4-benzothiazine (Va) is described. Acylation of Va was shown to proceed without opening of the thiazine ring. Preparation of the O-benzoyl, N-benzoyl, and O,N-dibenzoyl derivatives of 2-(β-hydroxyethyl-mercapto)aniline (VIII) has permitted clarification of the confusion in the literature with respect to the derivatives of Va and VIII. Compound XVIII, the 1,1-dioxide of IIIa, undergoes C-alkylation at the 2-position when treated with alkyl halides, rather than O-alkylation as previously suggested.


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