다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

J. Appl. Cryst.の発刊に際して

Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.

Multicomponent Reactions with Isocyanides.

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Principles Of Fluorescence Spectroscopy

ion. The oxidative addition mechanism was originally proposed22i because of the lack of a strong rate dependence on polar factors and on the acidity of the medium. Later, however, the electrophilic substitution mechanism also was proposed. Recently, the oxidative addition mechanism was confirmed by investigations into the decomposition and protonolysis of alkylplatinum complexes, which are the reverse of alkane activation. There are two routes which operate in the decomposition of the dimethylplatinum(IV) complex Cs2Pt(CH3)2Cl4. The first route leads to chloride-induced reductive elimination and produces methyl chloride and methane. The second route leads to the formation of ethane. There is strong kinetic evidence that the ethane is produced by the decomposition of an ethylhydridoplatinum(IV) complex formed from the initial dimethylplatinum(IV) complex. In D2O-DCl, the ethane which is formed contains several D atoms and has practically the same multiple exchange parameter and distribution as does an ethane which has undergone platinum(II)-catalyzed H-D exchange with D2O. Moreover, ethyl chloride is formed competitively with H-D exchange in the presence of platinum(IV). From the principle of microscopic reversibility it follows that the same ethylhydridoplatinum(IV) complex is the intermediate in the reaction of ethane with platinum(II). Important results were obtained by Labinger and Bercaw62c in the investigation of the protonolysis mechanism of several alkylplatinum(II) complexes at low temperatures. These reactions are important because they could model the microscopic reverse of C-H activation by platinum(II) complexes. Alkylhydridoplatinum(IV) complexes were observed as intermediates in certain cases, such as when the complex (tmeda)Pt(CH2Ph)Cl or (tmeda)PtMe2 (tmeda ) N,N,N′,N′-tetramethylenediamine) was treated with HCl in CD2Cl2 or CD3OD, respectively. In some cases H-D exchange took place between the methyl groups on platinum and the, CD3OD prior to methane loss. On the basis of the kinetic results, a common mechanism was proposed to operate in all the reactions: (1) protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, fivecoordinate platinum(IV) species, (3) reductive C-H bond formation, producing a platinum(II) alkane σ-complex, and (4) loss of the alkane either through an associative or dissociative substitution pathway. These results implicate the presence of both alkane σ-complexes and alkylhydridoplatinum(IV) complexes as intermediates in the Pt(II)-induced C-H activation reactions. Thus, the first step in the alkane activation reaction is formation of a σ-complex with the alkane, which then undergoes oxidative addition to produce an alkylhydrido complex. Reversible interconversion of these intermediates, together with reversible deprotonation of the alkylhydridoplatinum(IV) complexes, leads to multiple H-D exchange

Activation of c-h bonds by metal complexes

Magnetic Properties Diagnostic for the Existence of Iron(II)-Iron(II) Bonds in Dinuclear Complexes Which Derive from Stepwise Insertion Reactions on Unsupported Iron-Aryl Bonds

Radical annulations and cyclisations with isonitriles: the fate of the intermediate imidoyl and cyclohexadienyl radicals

Photoinduced cleavage of the residual N-N bond in the dimetallahydrazone 1 (Mes=2,4,6-Me3 C6 H2 ) led to a transient monomeric nitrido complex, which reacts further with 1 to form 2. Compound 1 was synthesized by the reductive arylation of MoCl4 ⋅DME by MesMgBr under an N2 atmosphere.

Photochemical Activation of the N≡N Bond in a Dimolybdenum–Dinitrogen Complex: Formation of a Molybdenum Nitride

The Zr-C bond chem. and, particularly, its migration properties were studied where the metal is bonded to the dibenzotetramethyltetraaza[14]annulene (tmtaa) dianion in the model complexes cis-[Zr(tmtaa)R2]. In this respect the [Zr(tmtaa)] fragment was analyzed in comparison with the known [Cp2Zr] moiety, with the support of an extended Hueckel anal. The synthesis of [Zr(tmtaa)R2] (R = Me, 2; R = CH2Ph, 3) (shown as structure I) from [Zr(tmtaa)Cl2] (1) was achieved under highly controlled reaction conditions. Complexes 2 and 3 are thermally labile, and one of the alkyl groups undergoes a thermally-induced migration to one of the imino groups, leading to a trianionic ligand [Zr(R-tmtaa)R] (R = Me, 4; R = CH2Ph, 5). The nature of such complexes was elucidated by an x-ray anal. on the THF-solvated form of 4, [Zr(Me-tmtaa)(Me)(THF)] (6). Nucleophiles are even more effective in inducing the alkyl migration to the ligand. In the presence of THF or pyridine 5 may be easily converted to [Zr(R2-tmtaa)] (R = CH2Ph, 7), in which both alkyl groups have migrated to the imino groups of the ligand. The use of an excess of LiMe during the alkylation of 1 gave [Zr(Me2-tmtaa)¬?¬?¬?Li(THF)2] (8) via the intermediacy of 4. Complex 8 is a bifunctional carrier of LiMe. The general consequences of two electrophilic sites on the ligand, eventually, in competition with the electrophilic metal were analyzed. The net charge and electrophilic index are significantly higher for the metal in [Cp2Zr]2+ than in [Zr(tmtaa)]2+. The relatively higher thermal inertness of 3 allowed the authors to study the migration of the alkyl group toward the unsatd. incoming nucleophiles, ButNC and CO. The reaction of 3 with ButNC gave the bis(??2-iminoacyl) compd. [Zr(tmtaa)(??2-C(Me):NBut)2]. The four low-lying d orbitals can accommodate the two ??2-iminoacyl groups. The reaction of 3 with Bu'NC led to the formation of the bis(y2-iminoacyl) compound [Zr(tmtaa)(v2-C(Me)=NBut)2T]h.e four low-lying d orbitals can accommodate the two y2-iminoacyl groups. The reaction of 3 with CO gave [Zr(tmtaa)(yz-OC(CH2Ph)~)(]1 1) via the intermediacy of a very reactive oxycarbene $-acyl compound and ultimately gave 12 and 13, illustrating the reactivity of both zirconium and the iminato carbons in the [Zr(tmtaa)] fragment. The crystallographic details are as follows: 3 is orthorhombic, space group Pnma, a = 16.028(3) A, b = 20.666(4) A, c = 9.018(2) A, a = p = y = 90°, Z = 4, and R = 0.063. 6 is monoclinic, space group P2l/n, a = 19.859(5) A, b = 14.771(5) A, c = 9.072(4) A, a = y = 90°, /3 = 93.85(3)", Z = 4, and R = 0.044. 7 is monoclinic, space group C2/c, a = 23.608(6) A, b = 9.529(3) A, c = 19.050(4) A, a = y = 90", p = 99.30(2)", Z = 4, and R = 0.046. 10 is triclinic, space group P i , a = 12.800(4) A, b = 15.795(5) A, c = 11.758(1) A, a = 91.8(2)", p = 93.56(1)", y = 97.81(2)", Z = 2, and R = 0.042.

Migratory Aptitude of the Zr-C Functionalities Bonded to a Macrocyclic Structure: Thermally- and Solvent-Assisted Intra- and Intermolecular Migrations in Dialkyl(dibenzotetramethyltetraazaannulene)zirconium(IV)

Oxazoline early transition metal complexes : functionalizable achiral titanium(iv), titanium(iii), zirconium(iv), vanadium(iii), and chiral zirconium( iv) bis(oxazoline) complexes

Corrado Rizzoli

Papers

Magnetic Properties Diagnostic for the Existence of Iron(II)-Iron(II) Bonds in Dinuclear Complexes Which Derive from Stepwise Insertion Reactions on Unsupported Iron-Aryl Bonds

Radical annulations and cyclisations with isonitriles: the fate of the intermediate imidoyl and cyclohexadienyl radicals

Photochemical Activation of the N≡N Bond in a Dimolybdenum–Dinitrogen Complex: Formation of a Molybdenum Nitride

Migratory Aptitude of the Zr-C Functionalities Bonded to a Macrocyclic Structure: Thermally- and Solvent-Assisted Intra- and Intermolecular Migrations in Dialkyl(dibenzotetramethyltetraazaannulene)zirconium(IV)

Oxazoline early transition metal complexes : functionalizable achiral titanium(iv), titanium(iii), zirconium(iv), vanadium(iii), and chiral zirconium( iv) bis(oxazoline) complexes