28118-33-4Relevant articles and documents
van Haverbeke et al.
, p. 53,54,55,61,62 (1975)
N′-(Arylsulfonyl)pyrazoline-1-carboxamidines as novel, neutral 5-hydroxytryptamine 6 receptor (5-HT6R) antagonists with unique structural features
Van Loevezijn, Arnold,Venhorst, Jennifer,Iwema Bakker, Wouter I.,De Korte, Cor G.,De Looff, Wouter,Verhoog, Stefan,Van Wees, Jan-Willem,Van Hoeve, Martijn,Van De Woestijne, Rob P.,Van Der Neut, Martina A. W.,Borst, Alice J. M.,Van Dongen, Maria J. P.,De Bruin, Natasja M. W. J.,Keizer, Hiskias G.,Kruse, Chris G.
experimental part, p. 7030 - 7054 (2011/12/15)
The 5-HT6 receptor (5-HT6R) has been in the spotlight for several years regarding CNS-related diseases. We set out to discover novel, neutral 5-HT6R antagonists to improve off-target selectivity compared to basic amine-con
Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
, p. 4433 - 4451 (2008/02/09)
Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
Phase Transfer Catalysis without Solvent: Selective Mono- or Di-alkylation of Malononitrile
Diez-Barra, Enrique,Hoz, Antonio de la,Moreno, Andres,Sanchez-Verdu, Prado
, p. 2589 - 2592 (2007/10/02)
Monoalkyl and symmetrical or unsymmetrical dialkylmalononitriles have been prepared selectively by phase transfer catalysis in the absence of solvent.Exclusive formation of a particular compound is achieved in all cases except for benzylmalononitrile 2f (79percent) and prop-2-ynylmalononitrile 2g (62percent).
