21906-31-0Relevant articles and documents
Markovnikov Wacker-Tsuji Oxidation of Allyl(hetero)arenes and Application in a One-Pot Photo-Metal-Biocatalytic Approach to Enantioenriched Amines and Alcohols
Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
, p. 4096 - 4108 (2021/08/19)
The Wacker-Tsuji aerobic oxidation of various allyl(hetero)arenes under photocatalytic conditions to form the corresponding methyl ketones is presented. By using a palladium complex [PdCl2(MeCN)2] and the photosensitizer [Acr-Mes]ClO4 in aqueous medium and at room temperature, and by simple irradiation with blue led light, the desired carbonyl compounds were synthesized with high conversions (>80%) and excellent selectivities (>90%). The key process was the transient formation of Pd nanoparticles that can activate oxygen, thus recycling the Pd(II) species necessary in the Wacker oxidative reaction. While light irradiation was strictly mandatory, the addition of the photocatalyst improved the reaction selectivity, due to the formation of the starting allyl(hetero)arene from some of the obtained by-products, thus entering back in the Wacker-Tsuji catalytic cycle. Once optimized, the oxidation reaction was combined in a one-pot two-step sequential protocol with an enzymatic transformation. Depending on the biocatalyst employed, i. e. an amine transaminase or an alcohol dehydrogenase, the corresponding (R)- and (S)-1-arylpropan-2-amines or 1-arylpropan-2-ols, respectively, could be synthesized in most cases with high yields (>70%) and in enantiopure form. Finally, an application of this photo-metal-biocatalytic strategy has been demonstrated in order to get access in a straightforward manner to selegiline, an anti-Parkinson drug. (Figure presented.).
Sequential Suzuki-Miyaura Coupling/Lewis Acid-Catalyzed Cyclization: An Entry to Functionalized Cycloalkane-Fused Naphthalenes
Mahecha-Mahecha, Camilo,Lecornué, Frédéric,Akinari, Sumita,Charote, Thomas,Gamba-Sánchez, Diego,Ohwada, Tomohiko,Thibaudeau, Sébastien
supporting information, p. 6267 - 6271 (2020/09/02)
Functionalized angular cycloalkane-fused naphthalenes were prepared using a two-step process involving a Pd-catalyzed Suzuki-Miyaura coupling of aryl pinacol boronates and vinyl triflates followed by a boron trifluoride etherate-catalyzed cycloaromatization.
Construction of 1,3-Dithio-Substituted Tetralins by [1,5]-Alkylthio Group Transfer Mediated Skeletal Rearrangement
Hisano, Naoya,Kamei, Yuto,Kansaku, Yaoki,Yamanaka, Masahiro,Mori, Keiji
supporting information, p. 4223 - 4226 (2018/07/29)
A novel skeletal rearrangement involving a [1,5]-alkylthio group transfer/cyclization sequence is described. Treatment of benzylidene malonates having a thioketal moiety at the homobenzyl position with a catalytic amount of Sc(OTf)3 afforded alkylthio group rearranged adducts in good chemical yields. Detailed investigation of the reaction mechanism revealed that an intramolecular conjugate addition/ring opening sequence (not through-space transfer) is the key to achieving this reaction.
Stereoselective synthesis of a: Podophyllum lignan core by intramolecular reductive nickel-catalysis
Xiao, Jian,Cong, Xiao-Wei,Yang, Gui-Zhen,Wang, Ya-Wen,Peng, Yu
supporting information, p. 2040 - 2043 (2018/03/01)
A Ni-catalyzed reductive cascade to a diastereocontrolled construction of THN[2,3-c]furan, is developed. The mild reaction conditions led to the tolerance of broad functional groups that can be placed in almost every position of this skeleton with good yields. The conformational control for the observed trans- or cis-fused selectivity during this tandem cyclization-coupling is also proposed.
Free radical-mediated aryl amination and its use in a convergent [3 + 2] strategy for enantioselective indoline α-amino acid synthesis
Viswanathan, Rajesh,Prabhakaran, Erode N.,Plotkin, Michael A.,Johnston, Jeffrey N.
, p. 163 - 168 (2007/10/03)
The scope of aryl radical additions to the nitrogen of azomethines is described. Aryl, trifluoromethyl alkyl, and α,β-unsaturated ketimines engage in regioselective aryl-nitrogen bond formation via 5-exo cyclizations of an aryl radical to azomethine nitrogen. Selectivity for carbon-nitrogen over carbon-carbon bond formation is generally high (>95:5) and competes only with direct aryl radical reduction by stannane (0-10%). α-Ketoimines are a promising new class of carbon radical acceptors for which no competitive aryl radical reduction is observed. The reaction conditions are pH-neutral and are therefore among the mildest methods available for amination of an aromatic ring. The ketimines examined did not suffer from competitive reduction by stannane, offering an advantage over the use of diazo and azide functional groups as nitrogen sources for carbon radicals. The free radical-mediated aryl amination was sequenced with the O'Donnell phase transfer-catalyzed enantioselective alkylation strategy of glycinyl imine to provide either enantiomer of indoline α-amino acids with high ee. These new constrained phenyl alanine derivatives are now readily available for evaluation across a variety of applications.
Mass spectrometric investigations on phenylacetic acid derivatives, IV: Loss of ortho-substituents from ionized phenyl-2-propanones upon electron impact
Striegel,Mayer,Wiegrebe,Schlunegger,Siegrist,Aebi
, p. 751 - 760 (2007/10/02)
In the gas phase, the phenyl-2-propanone molecules 2a-4a lose upon electron impact chloro-, bromo-, and iodo-radicals specifically at the orthopOsition of the phenyl group giving rise to strong (M-Hal.)+-ions (70/12 eV; 1st and 2nd FFR) of identical structure as confirmed by their MIKE-CAD-spectra. The daughter ions at m/z 133 from o-chlorophenyl-2-propanone (2a) and 2,2-dimethyl-2,3-dihydro[b]furane (11) are structurally similar but not identical (similarity index 99.8). The collisionally activated (2nd FFR) (M-Br.)+-ions from o-bromophenyl-2-propanone (3a) and 1-bromo-1-phenyl-2-propanone (12) produce virtually congruent spectra. The most impOrtant subsequent fragmentation of the (M-Hal-)+-ions from 2a-4a is the loss of CO which incorporates the C-atom of the carbonyl group exclusively (13C labelling). Mechanistic aspects of the fragmentation sequences are discussed (Figs. 5 and 8).
Aralykyl (arylethynyl)aralkyl amines and their use as vasodilators and antihypertensives
-
, (2008/06/13)
Acetylenes of the formula (I): STR1 wherein Y, m, R1, R2 q, Alk, R3, n and R4 are as defined herein and Ar1 and Ar2 are aromatic, including the salts and ammonium derivatives of formula (I), in treating angina, hypertension and cardiac arrhythmias. Pharmaceutical compositions, methods of use and synthesis and novel intermediates are also part of the invention.
Arylation and 1-Alkenylation on α-Position of Ketones via Tributyltin Enolates Catalyzed by Palladium Complex
Kosugi, Masanori,Hagiwara, Isao,Sumiya, Takao,Migita, Toshihiko
, p. 241 - 246 (2007/10/02)
The reaction of tributyltin enolates, prepared from tributyltin methoxide and enol acetates in situ, with aryl and 1-alkenyl bromides in the presence of dichlorobis(tri-o-tolylphosphine)palladium was found to give α-aryl and α-(1-alkenyl) ketones, respectively, in good yields with essentially complete retention of the enol acetate regiochemistry.
ACETONYLATION AROMATIQUE HOMOLYTIQUE
Gardrat, C.
, p. 897 - 902 (2007/10/02)
Treatment of monosubstituted benzene derivatives with acetone and manganese(III) acetate in acetic acid gave rise to products of homolytic aromatic substitution in fairly good yields and high purity except for toluene.Isomer distribution, relative rates and partial rate factors were determeined for toluene, anisole, chlorobenzene, bromobenzene and benzonitrile.A Hammet plot of the logarithm of the partial rate factors for meta and para positions vs. ?-constants gave a slope ρ of -1.74 +/- 0.40 (confidence interval at the level 95percent).When using ?+-constants the slope becomes ρ+ = -1.25 +/- 0.36.The negative velues of ρ and ρ+ indicated that the acetonyl radical has an appreciable electrophilic character.
