摘要:
A process for preparing polycyclic aromatic compounds by cross-coupling aromatic boron compounds with aromatic halogen compounds or perfluoroalkylsulfonates in the presence of metallic palladium as catalyst comprises adding to the reaction a) at least one water-soluble complexing ligand and b) sufficient water for the reaction mixture to form an aqueous phase. The reaction of the invention proceeds chemoselectively so that even electrophilic groups such as esters or nitriles do not have an adverse effect on the course of the reaction. The use according to the invention of a water-soluble complexing ligand in an aqueous phase enables polycyclic aromatic compounds to be prepared in very good yields and at the same time very high purity, in particular without contamination by the complexing ligands.
摘要:
Process for cross-coupling aromatic boron compounds with aromatic halogen compounds or perfluoroalkylsulfonates.In a process for preparing polycyclic aromatic compounds by cross-coupling aromatic boron compounds with aromatic halogen compounds or perfluoroalkylsulfonates under palladium catalysis in the presence of at least one water-soluble complex ligand, the reaction medium comprises an aqueous and an organic phase and the palladium is added in the form of a palladium compound soluble in the organic phase.Polycyclic aromatic compounds can thus be prepared economically and in very good yields and simultaneously very high purity, in particular without contamination by the complexing ligands.
摘要:
The present invention relates to a process for stabilizing 4-halopyridines of the formula (I) by adding a secondary and/or aliphatic or mixed aliphatic-aromatic tertiary amine, and mixtures comprising a compound of the formula (I) and a secondary and/or tertiary amine.
摘要:
A process is described for preparing compounds of formula (I) where R is H, optionally halogen-substituted alkyl, cycloalkyl, aryl, alkyl-aryl or heteroaryl, and, in alkyl and cycloalkyl, one or more CH2 groups may be replaced by —O—. The compounds of the formula (I) are valuable intermediates in the synthesis of PPAR agonists.
摘要:
A process for preparing polycyclic aromatic compounds by cross-coupling aromatic boronic acids with aromatic halogen compounds or perfluoroalkylsulfonates in the presence of metallic palladium, if desired applied to a support material, as catalyst, wherein the coupling is carried out in the presence of a ligand and a base. The process of the invention allows the yield of polycyclic aromatic compounds to be significantly increased in comparison with processes not using a ligand and thus allows a yield optimum for the Pd(0)-catalyzed cross-coupling of aromatic boronic acids with aromatic halogen compounds to be achieved.
摘要:
A smectic liquid-crystal mixture containing rod-shaped molecules having only one side chain and certain phenylpyrimidine derivatives. The liquid-crystal mixtures according to the invention are distinguished by a low melting point and a high S.sub.C /S.sub.A phase-transition temperature. The use of bisesters of the formula I allows the number of phenylpyrimidine derivatives in the mixtures according to the invention to be significantly reduced. Ferroelectric mixtures according to the invention have, in particular, high contrast, good alignment, a large margin, low flicker and a large angle in the chevron geometry.
摘要:
Process for preparing highly pure enantiomers of oxirane alcohols, which comprises recrystallizing a mixture of the isomeric oxirane alcohols, in which the desired enantiomer is present in an excess of at least 60% ee, in a solvent or solvent mixture at a temperature just below the melting point of the oxirane alcohol.Oxirane alcohols prepared according to the invention are distinguished by high enantiomer purity. Ferroelectric liquid crystals, which contain highly pure enantiomers of oxirane alcohols according to the invention and/or derivatives derived therefrom, have particularly short switching times.
摘要:
1-Fluoro-5,6,7,8-tetrahydroisoquinoline derivatives, and their use in liquid-crystalline mixtures1-Fluoro-5,6,7,8-tetrahydroisoquinoline derivatives of the formula (I)R.sup.1 ( --M.sup.1).sub.a (--A.sup.1 --M.sup.2).sub.b (--A.sup.2 --M.sup.3).sub.c --B(--M.sup.4 --A.sup.3).sub.d (--M.sup.5 --A.sup.4).sub.e (--M.sup.6 .sub.f --R.sup.2 (I)in which the symbols and indices have the following meanings:the group B is ##STR1## R.sup.1 and R.sup.2 are, for example, alkyl radicals having 1 to 20 carbon atoms;M.sup.1, M.sup.2, M.sup.3, M.sup.4, M.sup.5 and M.sup.6 are, for example, --O--, --CO--O--, --O--CO-- or a single bond;A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are, for example, 1,4-phenylene, pyrimidine-2,5-diyl or trans-1,4-cyclohexylene, anda, b, c, d, e and f are zero or one, with the proviso that the sum of b, c, d and e is 0, 1 or 2.The compounds of the formula (I) are colorless in the pure state and generally form liquid-crystalline mesophases in a temperature range which is favorably located for electro-optical use. They are stable chemically, thermally and to light.