A method for the regioselective 1,2-arylboration of 1,3-butadiene, a feedstock chemical, is reported. The reactions result in the formation of products that can be easily elaborated to other structures. The mechanistic details of this process are also discussed. 相似文献
An efficient procedure for the regioselective synthesis of secondary alcohol alkoxylates from 2,2,4-trimethyl-1,3-pentanediol
(TMPD) is described. TMPD was reacted with propylene oxide followed by ethylene oxide in the presence of a catalytic amount
of alkali metal hydroxide to form secondary alcohol alkoxylates. Instead of a mixture of compounds resulting from the reaction
of TMPD and propylene oxide, the primary hydroxyl group of the TMPD reacted to form predominantly 2,2,4-trimethyl-3-hydroxypentylpropoxylate
as the major product. On further ethoxylation the less hindered secondary hydroxyl group of the 2,2,4-trimethyl-3-hydroxypentylpropoxylate
reacted predominantly. 13C NMR indicated that the secondary hydroxyl group (96.2 mol%) of TMPD remained unreacted during alkoxylation. 相似文献
The novel complex (4-cyclooctene-l-yl)- bis(trifluoroacetamido) nickel oligomerizes ethene to olefins of about 85% linearity. Unusual high activities of 11500 mol ethene/mol nickel were obtained. Also higher α-olefins such as propene, butene or octene could be oligomerized yielding 70-80% linear dimers. By using (4-cyclooctene-1-yl)(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) nickel activated by BF3 the bulky olefin neohexene was converted selectively into dimers, which are linear, considering the C-C-linkage. 相似文献
Alcohol dehydrogenases (ADH) are important tools for generating chiral α-hydroxyketones. Previously, only the ADH of Thauera aromatica was known to convert cyclic α-diketones with appropriate preference. Here, we extend the spectrum of suitable enzymes by three alcohol dehydrogenases from Citrifermentans bemidjiense (CibADH), Deferrisoma camini (DecADH), and Thauera phenylacetica (ThpADH). Of these, DecADH is characterized by very high thermostability; CibADH and ThpADH convert α-halogenated cyclohexanones with increased activity. Otherwise, however, the substrate spectrum of all four ADHs is highly conserved. Structural considerations led to the conclusion that conversion of diketones requires not only the expansion of the active site into a large binding pocket, but also the circumferential modification of almost all amino acid residues that form the first shell of the binding pocket. The constellation appears to be overall highly specific for the relative positioning of the carbonyl functions and the size of the C-ring. 相似文献
A highly regioselective catalytic approach has been developed towards carbamates derived from cyclic organic carbonates by reaction of the latter with amine reagents under organocatalytic control. For various combinations of carbonate and amine substrates, an organocatalyst (TBD: 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene) was used to increase the reaction kinetics while exerting excellent regioselective control. The current method is the first general approach towards the control over the regioselectivity of this reaction using a wide variety of easily accessed substituted organic carbonates.
The biologically important, FAD-containing acyl-coenzyme A (CoA) dehydrogenases (ACAD) usually catalyze the anti-1,2-elimination of a proton and a hydride of aliphatic CoA thioesters. Here, we report on the structure and function of an ACAD from anaerobic bacteria catalyzing the unprecedented 1,4-elimination at C3 and C6 of cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA) to cyclohex-1,5-diene-1-carboxyl-CoA (Ch1,5CoA) and at C3 and C4 of the latter to benzoyl-CoA. Based on high-resolution Ch1CoA dehydrogenase crystal structures, the unorthodox reactivity is explained by the presence of a catalytic aspartate base (D91) at C3, and by eliminating the catalytic glutamate base at C1. Moreover, C6 of Ch1CoA and C4 of Ch1,5CoA are positioned towards FAD-N5 to favor the biologically relevant C3,C6- over the C3,C4-dehydrogenation activity. The C1,C2-dehydrogenation activity was regained by structure-inspired amino acid exchanges. The results provide the structural rationale for the extended catalytic repertoire of ACADs and offer previously unknown biocatalytic options for the synthesis of cyclic 1,3-diene building blocks. 相似文献
1,3-Dichlorobenzo[f]quinoline 2 was obtained from 1-hydroxybenzo[f]quinolin-3-one 1. Nucleophilic substitution, hydrolysis, hydrazinolysis and azidation reactions of compound 2 have been studied and found regioselective. Also, 1-aminobenzo[f]quinolinone 11 was obtained and used to prepare the benzoquinolinylthiourea derivative 12, naphthonaphthyridinedione 13, benzoquinolinylhydrazonoquinoline 15 and benzo[f]-quinolinyl enamine 17. 相似文献
An efficient alkylation method of functionalized alkyl halides under mild nickel‐catalyzed C(sp3) C(sp2) Suzuki cross‐coupling conditions is described. The features of this approach are excellent functional group compatibility, low cost nickel catalyst, and the use of a mild base. This is also the first successful example of the nickel‐catalyzed direct 2,2‐difluoroethylation or 2,2,2‐trifluoroethylation of aryl‐/heteroarylboronic acids.
Catalysis Letters - In the present paper, an efficient Cu-catalyzed regioselective acylation of indoles with phenylglyoxals was developed which is the first example of indolyl diketones synthesis... 相似文献
Abstract Some β-diketones such as LIX 51 (Henkel KGaA), Hostarex DK 16 (Hoechst AG), LIX 54 (Henkel KGaA), and MX 80A (Sigma Innovation, Sweden) were developed for technical applications (1) but only LIX 54 is commercially available. The use of LIX 54 to separate copper from ammoniacal etch solutions is described by patent applications (2–4) and an information paper of Henkel KGaA. The extraction of transition metals with LIX 54 was studied by Ramesh et al. (5). LIX 54 in a mixture with neutral donor ligands also proved suitable for the extraction of lanthanide elements (6). The active component of LIX 54 and MX 80A was recently identified as a mixture of isomeric l-phenyl-3-iso-heptyl-1,3-propanediones (7, 8). Analogous P-diketones are easily available. 相似文献
Abstract The synthesis of two β-1 lignol dimers, 1,2-bis-(4-hydroxy-3-methoxyphenyl)-i,3-propanediol (Via) and l-(3-ethoxy-4-hydroxyphenyl)-2-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (VIb) was performed using the Ivan off Reaction in the key synthetic step. The erythro forms of Via and b were isolated as crystalline solids in yields of approximately 15%, while the threo isomers were obtained as oils. The ratio of threo: erythro isomers was approximately 3:1. 相似文献