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Multifunctional Building Blocks (multifunctional + building_block)
Selected AbstractsCopper-Catalyzed Asymmetric Allylic Alkylation of Halocrotonates: Efficient Synthesis of Versatile Chiral Multifunctional Building BlocksADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Hartog, Tim den Abstract The highly enantioselective synthesis of ,-methyl-substituted esters is reported in up to 90% yield and up to 99% ee using copper-TaniaPhos as chiral catalyst. The transformation proved scalable to at least 6.6,mmol (1.7,g scale). The products of this transformation have been further elaborated to multifunctional building blocks with a single (branched esters and acids) or multiple stereogenic centers (vicinal dimethyl esters, as well as, hydroxy- or iodo-substituted lactones). [source] ChemInform Abstract: Copper-Catalyzed Asymmetric Allylic Alkylation of Halocrotonates: Efficient Synthesis of Versatile Chiral Multifunctional Building Blocks.CHEMINFORM, Issue 35 2010Tim den Hartog Abstract The highly enantioselective synthesis of ,-methyl-substituted ester (III) is reported. [source] Copper-Catalyzed Asymmetric Allylic Alkylation of Halocrotonates: Efficient Synthesis of Versatile Chiral Multifunctional Building BlocksADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Hartog, Tim den Abstract The highly enantioselective synthesis of ,-methyl-substituted esters is reported in up to 90% yield and up to 99% ee using copper-TaniaPhos as chiral catalyst. The transformation proved scalable to at least 6.6,mmol (1.7,g scale). The products of this transformation have been further elaborated to multifunctional building blocks with a single (branched esters and acids) or multiple stereogenic centers (vicinal dimethyl esters, as well as, hydroxy- or iodo-substituted lactones). [source] Asymmetric Hydrogenation of ,,,-Unsaturated Ester- PhosphonatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Yange Huang Abstract The rhodium-catalyzed asymmetric hydrogenation of readily available ,,,-unsaturated ester-phosphonates affords the corresponding ,-chiral phosphonates in excellent yield and ee. The resulting products are useful multifunctional building blocks applied in the synthesis of physiologically active compounds. [source] The Tautomeric Forms of Cyameluric Acid Derivatives,CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2007Nadia Abstract The tautomerism of cyameluric acid C6N7O3H3 (1,a), cyamelurates and other heptazine derivatives has recently been studied by several theoretical investigations. In this experimental study we prepared stannyl and silyl derivatives of cyameluric acid (1,a): C6N7O3[Sn(C4H9)3]3 (3,a), C6N7O3[Sn(C2H5)3]3 (3,b), and C6N7O3[Si(CH3)3]3 (4). In order to investigate the structure of 1,a the mono- and dipotassium cyamelurate hydrates K(C6N7O3H2),2,H2O (5) and K2(C6N7O3H),1,H2O (6) were synthesized by UV/Vis-controlled titration of a potassium cyamelurate solution with aqueous hydrochloric acid. Compounds 3,6 were characterized by FTIR and solid-state NMR spectroscopy as well as simultaneous thermal analysis (TGA, DTA). The single crystal X-ray structures of the salts 5 and 6 show that the hydrogen atoms in both anions are localized on the peripheral nitrogen atoms. This indicates,in combination with the solid-state NMR studies,that the most stable tautomer of solid 1,a is the triketo form with C3h symmetry. However, derivatives of both the hydroxyl and the amido tautomers may be formed depending on the substituent atoms: The spectroscopic data and single crystal structures of compounds C6N7O3[Si(CH3)3]3 (4) and the solvate C6N7O3[Sn(C2H5)3]3,C2H4Cl2 (3,b,) show that the former is derived from the symmetric trihydroxy form of 1,a, while 3,b, crystallizes as a chain-like polymer, which contains the tin atoms as multifunctional building blocks, that is, bridging pentacoordinated Et3SnO2 and Et3SnON units as well as non-bridging four-coordinated Et3SnN units. The cyameluric nucleus is part of the polymeric chains of C6N7O3[Sn(C2H5)3]3,C2H4Cl2 (3,b,), by the action of both tautomeric forms of cyameluric acid, the amide and the ester form. [source] | ||||||||||