Alkoxy group

About: Alkoxy group is a research topic. Over the lifetime, 63938 publications have been published within this topic receiving 489778 citations.

A rationally designed universal catalyst for Suzuki-Miyaura coupling processes

Abstract: Despite advances in the Suzuki–Miyaura cross-coupling process, the need for an operationally simple and general system remains. The minimum criteria for an optimum system that must be met include: 1) a broad substrate scope, 2) the ability to make truly hindered biaryls, 3) the ability to operate at low levels of catalyst for a range of substrates not just with the most simple examples (e.g., other than phenyl boronic acid), and 4) the ability to operate at room temperature. Moreover, it is most desirable to develop protocols that do not necessitate the use of a glovebox. Herein we report a catalyst system based on a new ligand that meets the above four criteria, has unprecedented scope, reactivity, and stability, uses only commercially available, air-stable components, and is experimentally simple to employ. Our previous work on cross-coupling methodology demonstrated that dialkylphosphanylbiphenyls were excellent supporting ligands. We have reported that these can be prepared by the addition of an aryl Grignard reagent to an insitu-generated benzyne intermediate, followed by trapping of the newly formed organomagnesium complex with ClPR2. [3] The thought process that led to the design of the new ligand 1 is shown in Scheme 1. Mechanistic studies in our laboratory indicated that the elimination of ortho hydrogens on the bottom ring (that not bearing the dialkylphosphanyl group) was important for catalyst activity and longevity. We believe that this is due to two effects: 1) prevention of cyclometalation (to form a palladacycle), which diminishes catalyst lifetime, and 2) increased steric bulk relative to complexes with two ortho hydrogens. We also feel that it is important that the two methoxy groups are smaller in size than two alkyl groups as in our previously reported ligands. Moreover, the lone pairs of the alkoxy groups might interact with the Pd center and/or add electron density to the ligand backbone. The latter could be important as the interaction of the metal with the bottom ring is well documented and could help stabilize intermediate complexes. Furthermore, the 1,3-dimethoxybenzene moiety offers the advantage that it can be installed by means

Metal complex compounds

Abstract: A monocyclopentadienyl or substituted monocyclopentadienyl metal complex containing compound useful as a polymerization catalyst corresponding to the formula: CpMX.sub.n.sup.+ A.sup.- wherein: Cp is a single η 5 -cyclopentadienyl or η 5 -substituted cyclopentadienyl group optionally covalently bonded to M through a substituent; M is a metal of Group 3-10 or the Lanthanide Series of the Periodic Table bound in an η 5 bonding mode to the cyclopentadienyl or substituted cyclopentadienyl group; X each occurrence independently is selected from the group consisting of hydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide, siloxy, neutral Lewis base ligands and combinations thereof having up to 20 non-hydrogen atoms, and optionally one X together with Cp forms a metallocycle with M; R is alkyl or aryl of up to 10 carbons; n is one or two depending on the valence of M; and A is a noncoordinating, compatible anion of a Bronsted acid salt.

Dinucleoside phosphinates and their pharmaceutical compositions

Abstract: A dinucleotide analogue of formula ##STR1## where B1 and B2 are each independently a monovalent nucleoside base radical; R1 is R1 a or Z; R1 a, R2, R3 and R4 are each independently hydrogen, halogen or hydroxy; R5 is R5 a or Z; R6 is hydrogen or R6 a ; R7 is hydrogen, alkyl-N,N-dialkylphosphoramidyl or R7 a, R8 is R8 a or Z, or the indicated R7 O and R8 together denote an isopropylidenedioxy group; R5 a and R8 a are each independently hydrogen, halogen, hydroxy, --OR10, --OCOR10 or silyloxy substituted by three C1 -C15 hydrocarbyl groups; R6 a and R7 a are each independently a C1 -C10 aliphatic radical, a C6 -C15 aromatic radical, a C7 -C30 araliphatic radical, --COR11, --SO2 R11 or silyl substituted by three C1 -C15 hydrocarbyl groups; R9 is hydrogen, a C1 -C8 aliphatic radical, a C3 -C8 cycloaliphatic radical, a C6 -C15 aromatic radical, a C7 -C13 araliphatic radical, an alkali metal ion or an ammonium ion; R10 and R11 are each independently a C1 -C10 aliphatic radical, a C3 -C8 cycloaliphatic radical, a C6 -C15 aromatic radical or a C7 -C16 araliphatic radical; Rx and Ry are independently hydrogen, halogen, hydroxy, a C1 -C10 alkyl, C2 -C10 alkenyl, C3 -C8 cycloalkyl, C6 -C15 aryl, C7 -C16 aralkyl, C1 -C10 alkoxy, C2 -C10 alkenoxy, C6 -C10 aryloxy or C7 -C16 aralkyloxy group, which is substituted or unsubstituted, or --OCORz ; Rz is a substituted or unsubstituted C1 -C10 alkyl, C2 -C10 alkenyl, C3 -C8 cycloalkyl, C6 -C15 aryl or C7 -C16 aralkyl group; and Z is C6 -C10 aryloxythiocarbonyloxy, the C6 -C10 aryl group being substituted or unsubstituted.

Oxidation hair dye containing 4,5-diaminopyrazole derivatives and novel 4,5-diaminopyrazole derivatives and process for their production

Abstract: Agents for the oxidative dyeing of hair based on a developer-coupler combination containing as the developer a 4,5-diaminopyrazole derivative of general formula (I) in which R1 is halogen, C?1?-C4 alkyl, C1-C4 alkoxy and R?2? is hydrogen, C?1?-C4 alkyl, C2-C4 hydroxyalkyl, or their physiologically acceptable, water-soluble salts, and novel 4,5-diaminopyrazole derivatives.