36597-09-8Relevant articles and documents
Single-Flask Multicomponent Palladium-Catalyzed α,γ-Coupling of Ketone Enolates: Facile Preparation of Complex Carbon Scaffolds
Grigalunas, Michael,Norrby, Per-Ola,Wiest, Olaf,Helquist, Paul
, p. 11822 - 11825 (2015)
A three-component palladium-catalyzed reaction sequence has been developed in which γ-substituted α,β-unsaturated products are obtained in a single flask by an α-alkenylation with either a subsequent γ-alkenylation or γ-arylation of a ketone enolate. Coup
Synthesis of Bifunctional Allylic Compounds by Using Cyclopropenes as Functionalized Allyl Equivalents
Mata, Sergio,López, Luis A.,Vicente, Rubén
, p. 11422 - 11426 (2018)
The synthesis of uncommon bifunctional allylic derivatives bearing a silane and an alcohol within the same allylic framework is reported. This method relies on the coupling of hydrosilanes with substituted and functionalized cyclopropenes, which deliver the allyl fragment. Rhodium(II) catalysts provide regioselective access to vinyl carbene intermediates, which easily undergo Si?H bond insertions. The transformation occurs with complete atom economy and shows a remarkably broad scope, including a intramolecular version for the synthesis of cyclic O?Si-linked compounds as well as the synthesis of the corresponding allyl amines.
Iron-Catalyzed Synthesis of Dihydronaphthalenones from Aromatic Oxime Esters
Zhang, Youcan,Yin, Zhiping,Wu, Xiao-Feng
supporting information, p. 3223 - 3227 (2019/05/10)
Herein, a convenient procedure on iron-catalyzed radical-mediated synthesis of dihydronaphthalenones from oxime esters has been developed. By using iron salt as a green and inexpensive catalyst, various α-aryl oxime esters were transformed into the corresponding dihydronaphthalenones in moderate to good yields with high chemo-selectivities. The reaction proceeds via 1,5-hydrogen atom transfer and then intramolecular radical cyclization sequence. (Figure presented.).
Asymmetric Aza-Wacker-Type Cyclization of N-Ts Hydrazine-Tethered Tetrasubstituted Olefins: Synthesis of Pyrazolines Bearing One Quaternary or Two Vicinal Stereocenters
Kou, Xuezhen,Shao, Qihang,Ye, Chenghao,Yang, Guoqiang,Zhang, Wanbin
supporting information, p. 7587 - 7597 (2018/06/04)
We have developed an asymmetric aza-Wacker-type cyclization of N-Ts hydrazine-tethered tetrasubstituted olefins, affording optically active pyrazolines bearing chiral tetrasubstituted carbon stereocenters. This reaction is tolerant to a broad range of substrates under mild reaction conditions, giving the desired chiral products with high enantioselectivities. Generation of two vicinal stereocenters on the C=C double bonds was also achieved with high selectivities, a process which has been rarely studied for Wacker-type reactions. A mechanistic study revealed that this aza-Wacker-type cyclization undergoes a syn-aminopalladation process. It was also found that for substrates bearing two linear alkyl substituents on the outer carbon atom of the olefin, both of which are larger than a methyl group, the alkyl substituent that is cis to the intranucleophilic group participates more readily in β-hydride elimination. When one of the two alkyl substituents on the outer carbon atom of the olefin is a methyl group, β-hydride elimination proceeds selectively at the methylene side, thus both diastereomers can be prepared via switching the configuration of the olefin. Furthermore, the product can be converted to a pharmaceutical compound in high yields over three steps.
Palladium-catalyzed alkenylation of ketone enolates under mild conditions
Grigalunas, Michael,Ankner, Tobias,Norrby, Per-Ola,Wiest, Olaf,Helquist, Paul
supporting information, p. 3970 - 3973 (2014/08/18)
A protocol for a mild, catalytic, intermolecular alkenylation of ketone enolates has been developed using a Pd/Q-Phos catalyst. Efficient intermolecular coupling of a variety of ketones with alkenyl bromides was achieved with a slight excess of LiHMDS and temperatures down to 0 °C.
Prins cyclization of α-bromoethers under basic conditions
Arpin, Patrice,Hill, Bryan,Larouche-Gauthier, Robin,Spino, Claude
, p. 1193 - 1201 (2014/01/06)
α-Bromoethers have been found to undergo Prins-type cyclization under basic conditions and without the need to add a promoter. The products are those derived from a Markovnikov addition on the pendant alkene. However, the stereochemistry and even the structure of the products sometimes differ from those expected with the classical Lewis-acid-catalyzed Prins reaction of acetals.
Stereoselective synthesis of β,γ-unsaturated ketones by acid-mediated Julia-type transformation from 2-(1-hydroxyalkyl)-1- alkylcyclopropanols
Nomura, Kenichi,Matsubara, Seijiro
experimental part, p. 1412 - 1414 (2009/04/06)
An efficient transformation of 2-(1-hydroxyalkyl)-1-alkylcyclopropanols, obtained from α,β-unsaturated ketones, to β,γ-unsaturated ketones was achieved by trifluoroacetic acid (TFA)-mediated reaction. Georg Thieme Verlag Stuttgart.
Catalytic addition-cyclization of alkyl ketones with 4-methyl-1-phenyl-4-penten-1-one
Ipatkin,Kovalev,Ignatenko,Nikishin
, p. 7971 - 7972 (2007/10/02)
Substituted 2-(β-oxoalkyl)tetrahydrofurans were obtained in one-step aldol-type reaction from alkyl ketones and 4-methyl-1-phenyl-4-penten-1-one in the presence of a catalytic system [RhCl(C2H4)2]2-SnCl2/s
Scope of alkoxymethyl radical cyclizations
Rawal,Singh,Dufour,Michoud
, p. 7718 - 7727 (2007/10/02)
We have explored different aspects of the cyclization capability of alkoxymethyl radicals and report here a full account of our investigations. The required radicals were generated from (phenylseleno)-methyl ethers (e.g., 6), which were prepared from homoallylic or bis-homoallylic alcohols by a two-step process. The alcohols were alkylated with (iodomethyl)tributylstannane. The stannanes were reacted with n-BuLi, and the resulting α-alkoxyanions were trapped with diphenyldiselenide to give the (phenylseleno)methyl ethers, which were stable to chromatography. When treated with tributyltin hydride, in the presence of a radical initiator, these precursors undergo a smooth cyclization to substituted tetrahydrofurans and tetrahydropyrans. Formation of the cyclization product was found to be the primary pathway even at relatively high tin hydride concentration. The diastereoselectivity of this cyclization was comparable to that observed in other radical cyclizations. The cis selectivity in cyclization of 6 increased gradually (up to 11:1) as the reaction temperature was lowered. The cyclization can be used for the synthesis of bicyclic and tricyclic compounds and can be incorporated in systems capable of tandem cyclizations.
