62269-44-7Relevant articles and documents
A Mass Spectrometric Study of the Dimethyl Ester Trimethylsilyl Enol Ether Derivatives of Some 3-Oxodicarboxylic Acids
Svendsen, John S.,Whist, Jon E.,Sydnes, Leiv K.
, p. 486 - 492 (1987)
The fragmentation pathways for the dimethyl ester trimethylsilyl enol ether derivatives of some 3-oxodicarboxylic acids have been found by using B/E and B2/E linked scans, collisional activated decomposition and isotope substitution techniques.The trimethylsilyloxy group strongly directs the decomposition processes, and induces a fragmentation pattern that intimately reflects the structure of the compounds.
Monomeric Dihydroanthraquinones: A Chemoenzymatic Approach and its (Bio)synthetic Implications for Bisanthraquinones
Saha, Nirmal,Mondal, Amit,Witte, Karina,Singh, Shailesh Kumar,Müller, Michael,Husain, Syed Masood
supporting information, p. 1283 - 1286 (2018/01/27)
Modified bisanthraquinones are complex dimeric natural products containing a cage-like structural motif. For their biosynthesis, monomeric dihydroanthraquinones have been proposed as key intermediates despite not being isolated from natural sources or synthesized as of yet. Here, isolation and characterization of dihydroemodin, as well as dihydrolunatin, synthesized by a biomimetic and chemoenzymatic approach using NADPH-dependent polyhydroxyanthracence reductase (PHAR) from Cochliobolus lunatus followed by Pb(OAc)4 oxidation is reported. Subsequent dimerization through a hetero-Diels–Alder reaction of the dihydroemodin and dihydrolunatin resulted in (?)-flavoskyrin (68 %) and (?)-lunaskyrin (62 %), respectively. Pyridine treatment of (?)-flavoskyrin and (?)-lunaskyrin gave (?)-rugulosin and (?)-2,2′-epi-cytoskyrin A in 64 % and 60 % yield, respectively, through a cascade that involves two dimeric intermediates. Implications of the described synthesis for the biosynthesis of bisanthraquinones by a combination of enzymatic and spontaneous steps are discussed.
Regio- and stereoselective nickel-catalyzed homoallylation of aldehydes with 1,3-dienes
Kimura, Masanari,Ezoe, Akihiro,Mori, Masahiko,Iwata, Keisuke,Tamaru, Yoshinao
, p. 8559 - 8568 (2007/10/03)
Ni(acac)2 catalyzes homoallylation of aldehydes with 1,3-dienes in the presence of triethylborane. Triethylborane serves as a reducing agent delivering a formal hydride to the C2 position of 1,3-dienes, thus generating a formal homoallyl anion species and enabling the novel homoallylation of aldehydes. The reaction proceeds smoothly at room temperature in the absence of any phosphane or nitrogen ligands and is highly regioselective and stereoselective for a wide variety combination of aldehydes and 1,3-dienes: e.g., isoprene and benzaldehyde combine to give a mixture of anti- and syn-1-phenyl-3-methyl-4-penten-1-ol (2.2) in a ratio of 15:1 in 90% yield. Under the conditions, sterically congested aliphatic aldehydes and ketones show low yields. In such cases, diethylzinc serves as a substitute for triethylborane and yields the expected products in good yields with similarly high regio- and stereoselectivity. 1,3-Cyclohexadiene is one exception among 24 kinds of dienes examined and undergoes allylation (not homoallylation) selectively.
