1,721,010 research outputs found
New Schiff Bases of the BIAN Family : from Symmetrical Biaryl Derivatives to Mixed, Alkyl, Chiral or Reduced Ligands and Components for Metal-Organic Frameworks
No full textNew hydrogenated Ar-BIAN (Ar-BIAN = bis-(arylimino)acenaphthene) derivatives and their involvement in catalytic reactions
No full textNew hydrogenated Ar-BIAN (Ar-BIAN = bis-(arylimino)acenaphthene) derivatives and their involvement in catalytic reactions
Mechanistic investigation of the palladium-phenanthroline catalyzed carbonylation of nitroarenes to carbamates and ureas : pentacoordinated intermediates and a bifunctional activation
No full textInfluence of Substituted Phenanthrolines on the Palladium Catalyzed Carbonylation of Nitrobenzene
No full textSynthesis of Triarylphosphines Having para –SH and –SMe Groups. Preparation of Their Complexes and Formation of a Monolayer on a Gold Surface
No full textThe phosphines P(C6H4-4-SR)3 (R = H, Me, 2-C5H9O) and (C6H4-4-SR)2PCH2CH2P(C6H4-4-SR)2 (R = H, Me) have been synthesized. The phosphines with –SMe groups can be prepared by reaction of 4-BrC6H4SMe with either BuLi or magnesium (to generate the corresponding Grignard compound) followed by reaction with PCl3 or Cl2PCH2CH2PCl2 respectively. The methyl group can be eliminated by reaction with sodium in liquid NH3. Other methods of protection/deprotection of the thiol group failed to afford the desired compounds. Reaction of 4-BrC6H4SH with dihydropyrane afforded the protected thiol 4-BrC6H4S-2-C5H9O from which the corresponding phosphine was successfully synthesized. However, attempts to remove the tetrahydropyranyl group by reaction with AgNO3-HCl, gave an insoluble polymer as product. Reaction of P(C6H4SR)3 (R = H, Me) with Ni(CO)4 affords the corresponding mono phosphine complex quantitatively. The complex with the unprotected thiol group can be absorbed on a gold surface and the corresponding CO bands were detected by grazing angle Fourier transform infrared reflection absorption spectroscopy (grazing angle FTIR-RAS). Reaction of Rh(acac)(CO)2 with (P(C6H4SR)3) (R = Me) affords the complex Rh(acac)(CO)(P(C6H4SR)3) (R = Me), but if R = H a polymer insoluble in any solvent was obtained. The same occurs in the case of PtCl2(CO)(DMSO). Apparently, once P(C6H4SH)3 is coordinated to a metal not in the zero oxidation state, oxidation of the thiol group to disulphide becomes very easy even in a dinitrogen atmospher
New Chiral Nitrogen Ligands Based on Amines Derived from -Pinene
No full textThe number of applications of bis-imines as ligands in homogeneous catalysis has much increased in recent years. Derivatives of acenaphthenequinone (R-BIAN) are especially useful for their chemical stability and rigidity. Until recently only Ar-BIAN ligands in which the aryl group contained electrondonating or moderately electronwithdrawing groups were known. We have recently expanded the available range of derivatives to ligands where the aryl group bears strongly electronwithdrawing substituents,1 two different aryl groups are present,2 and even to Alkyl-BIAN compounds.3,4 The latest had never been isolated before because an isomerization reaction occurred leading to their decomposition. We identified the cause of the decomposition in the ring strain of the five-membered ring of the acenaphthene moiety, which is partly released upon isomerization of the C=N double bond. The problem could be solved by employing ring-strained amines, for which this isomerization is thermodinamically unfavorable.3,4 Here we report the synthesis of a chiral cyclopropylamine derived from enantiomerically pure -pinene. The amine was obtained in good yields in four diastereomers. These can be separated by column chromatography. Two isomers are most abundant. One of them was employed in the synthesis of the corresponding BIAN derivative.
[1] Gasperini, M.; Ragaini, F.; Cenini, S. Organometallics, 2002, 21, 2950.
[2] Gasperini, M.; Ragaini, F.; Gazzola, E.; Caselli, A.; Macchi, P. Dalton Trans., 2004, 3376.
[3] Ragaini, F. ; Gasperini, M.;. Gallo, E.; Macchi, P. Chem. Commun., 2005, 1031.
[4] Ragaini, F.; Gasperini, M.; Parma, P.; Gallo, E.; Casati, N.; Macchi, P. New J. Chem. 2006, 30, 1046
Synthesis of indoles by cyclization of beta-nitrostyrenes catalyzed by palladium and with carbon monoxide as the reductant
No full textSynthesis of indoles by cyclization of beta-nitrostyrenes catalyzed by palladium and with carbon monoxide as the reductant
- …
