13955-60-7Relevant academic research and scientific papers
Transition metal mediated exo selective Diels-Alder reactions: Preparation of 2-cobalt-substituted 1,3-dienes containing C2 symmetric 2,3-dibenzobicyclo[2.2.2]octanedione dioxime equatorial ligands and their use in thermal and Lewis acid catalyzed 4 + 2 cycloadditions
Wright, Marcus W.,Welker, Mark E.
, p. 133 - 141 (1996)
The preparation of C2 symmetric 2,3-dibenzobicyclo[2.2.2]octanedione dioxime is reported. This ligand is then used in the preparation of a (pyridine)(glyoxime)2cobalt(III) chloride complex. The chloride is reduced to a cobaloxime anion which reacted with allenic electrophiles to produce (pyridine)(glyoxime)2cobalt-1,3-dienyl complexes. Thermal and Lewis acid catalyzed Diels-Alder reactions of these dienyl complexes as well as the complexes with glyoxime = diphenylglyoxime and dimethylglyoxime are reported. In most cases these Diels-Alder reactions are anti (exo) selective, and in many cases diastereoselectivities are >20:1. Cycloadduct demetalation reactions are also reported which preserve cycloaddition stereochemistry and provide cobalt complexes which can be recycled into the starting dienyl complex.
ALICYCLIC ESTER WITH MUSK FRAGRANCE
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Page/Page column 27, (2008/06/13)
A compound of formula (I) or (II) is disclosed, whereby, in formulas (I) and (II), R1 = an optionally-substituted (a) branched or unbranched C1 to C5 alkyl, or (b) branched or unbranched C2 to C5 alkylene, or (c) C3 to C5 cycloalkyl and in formula (II) the bond represented by a dotted line may be either a single- or a double-bond.
Synthesis of cobalt-substituted 1,3-diene complexes with unusual structures and their exo-selective Diels-Alder reactions
Wright, Marcus W.,Smalley Jr., Terrence L.,Welker, Mark E.,Rheingold, Arnold L.
, p. 6777 - 6791 (2007/10/02)
The synthesis and characterization (including crystallographic data) of several substituted-pyridine (Rpyr) cobalt bis(dimethylglyoxime) 1,3-butadiene complexes (R = H, tBu, 3,5-diMe, and N,N-dimethylamino) and their Diels-Alder reactions with a variety of dienophiles are reported here. The cobalt-carbon bonds in the Diels-Alder cycloadducts can be cleaved so that cobalt complexes as well as functionalized organic cycloadducts are recovered. Through these cobalt-carbon bond cleavage reactions, cobalt-diene complexes can serve as synthons for a variety of 1,3-dienes such as 1,3-butadiene, 2-(trimethylsiloxy)- 1,3-butadiene, iodoprene, (E)-1-methoxy-3-(trimethylsiloxy)-1,3-butadiene (Danishefsky's diene), and 1,2-dichloro-1,3-butadiene. The preparation of several cobalt-substituted 1,2- and 1,3-pentadiene complexes and highly exo-selective Diels-Alder reactions of the 1,3-pentadiene complexes are then discussed followed by demetalation reactions of these more highly substituted cobalt cycloadducts. These demetalation reactions maintain the stereochemical integrity found in the metal cycloadducts and also lead to cobalt recovery.
