20599-16-0Relevant articles and documents
Synthetic Photochemistry. A Synthesis of the Carbon Skeleton found in Taylorine from Mylia taylorii, using the Di-?-methane Rearrangement
Pattenden, Gerald,Whybrow, Derek
, p. 1046 - 1051 (1981)
Synthetic routes to the E- and Z-cyclopentenones (20) and (25), which incorporate photosensitive 1,4-diene systems, are described.Irradiation of the E-cyclopentenone (20) is shown to result in efficient regiospecific di-?-methane rearrangement (>70percent) to the vinylcyclopropane (26), which is then converted into trans-deoxytaylorione (28).Irradiation of the corresponding Z-cyclopentenone (25) also leads to (26), presumably by way of the E-cyclopentenone (20), produced by Z-E photoisomerisation.
Ruthenabenzene: A Robust Precatalyst
Gupta, Saswata,Su, Siyuan,Zhang, Yu,Liu, Peng,Wink, Donald J.,Lee, Daesung
supporting information, p. 7490 - 7500 (2021/05/26)
Metallaaromatics constitute a unique class of aromatic compounds where one or more transition metal elements are incorporated into the aromatic system, the parent of which is metallabenzene. One of the main concerns about metallabenzenes generally deals with the structural characterization related to their relative aromaticity compared to the carbon archetype. Transition metal-containing metallabenzenes are also implicated in certain catalytic processes such as alkyne metathesis polymerization; however, these transition metal-based metallaaromatic compounds have not been developed as a catalyst. Herein, we describe an effective strategy to generate diverse arrays of ruthenabenzenes and demonstrated them as an aromatic equivalent of the Grubbs-type ruthenium alkylidene catalysts. These ruthenabenzenes can be prepared via an enyne metathesis and metallotropic [1,3]-shift cascade process to form alkyne-chelated ruthenium alkylidene intermediates followed by spontaneous cycloaromatization. The aromatic nature of these complexes was confirmed by spectroscopic and X-ray crystallographic data, and the mechanistic pathways for the cycloaromatization process were studied by DFT calculations. These ruthenabenzenes display robust catalytic activity for metathesis and other transformations, which illustrates that metallabenzenes are not only compounds of structural and theoretical interests but also are a novel platform for new catalyst development.
Copper-Catalyzed Propargylation of Nitroalkanes
Kim, Raphael S.,Dinh-Nguyen, Linh V.,Shimkin, Kirk W.,Watson, Donald A.
supporting information, p. 8106 - 8110 (2020/11/02)
Using a commercially available, inexpensive, and abundant copper catalyst system, an efficient α-functionalization of nitroalkanes with propargyl bromides is now established. This mild and robust method is highly functional group tolerant and provides straightforward access to complex secondary and tertiary homopropargylic nitroalkanes. Moreover, the utility of these α-propargylated nitroalkanes is demonstrated through downstream functionalization to biologically relevant, five-membered N-heterocycles such as pyrroles and 2-pyrrolines.
A Highly Efficient Dimeric Manganese-Catalyzed Selective Hydroarylation of Internal Alkynes
Huang, Congcong,Li, Weipeng,Liu, Gengtu,Pang, Yubo,Xie, Jin,Yuan, Xiang-Ai
supporting information, p. 12789 - 12794 (2020/06/02)
We have developed a general and site-predictable manganese-catalyzed hydroarylation of internal alkynes in the presence of water, under an air atmosphere without the involvement of ligand. The unique catalytic feature of this reaction is highlighted by comparison with other widely used transition metal catalysts including palladium, rhodium, nickel, or copper. The simple operation, high efficiency and excellent functional group compatibility make this protocol practical for more than 90 structurally diverse internal alkynes, overcoming the influence of both electronic and steric effect of alkynes. Its exclusive regio- and chemoselectivity originates from the unique reactivity of the manganese-based catalyst towards an inherent double controlled strategy of sterically hindered propargyl alcohols without the installing of external directing groups. Its synthetic robustness and practicality have been illustrated by the concise synthesis of bervastatin, a hypolipidemic drug, and late-stage modification of complex alkynes with precise regioselectivity.
Palladium(II)/Lewis acid cocatalyzed oxidative annulation of 2-alkenylanilines and propargylic esters: An access to benzo[ b]azepines
Qiao, Hong,Zhang, Shengjun,Li, Kangkang,Cao, Zhengqiang,Zeng, Fanlong
, p. 10843 - 10851 (2019/09/12)
An attractive approach to valuable yet synthetically challenging benzo[b]azepines was established via palladium(II)/Lewis acid cocatalyzed oxidative [5 + 2] annulation of readily available 2-alkenylanilines and propargylic esters. The protocol features mild reaction conditions and good functional group tolerance, constituting an array of benzo[b]azepines in yields of 30-75%.
Flow rhodaelectro-catalyzed alkyne annulations by versatile C-H Activation: Mechanistic support for rhodium(III/IV)
Kong, Wei-Jun,Finger, Lars H.,Messinis, Antonis M.,Kuniyil, Rositha,Oliveira, Jo?o C.A.,Ackermann, Lutz
supporting information, p. 17198 - 17206 (2019/10/28)
A flow-metallaelectro-catalyzed C-H activation was realized in terms of robust rhodaelectro-catalyzed alkyne annulations. To this end, a modular electro-flow cell with a porous graphite felt anode was designed to ensure efficient turnover. Thereby, a variety of C-H/N-H functionalizations proved amenable for alkyne annulations with high levels of regioselectivity and functional group tolerance, viable in both an inter- or intramolecular manner. The electro-flow C-H activation allowed easy scale up, while in-operando kinetic analysis was accomplished by online flow-NMR spectroscopy. Mechanistic studies suggest an oxidatively induced reductive elimination pathway on rhodium(III) in an electrocatalytic regime.
Synthesis and Utility of 2,2-Dimethyl-2 H-pyrans: Dienes for Sequential Diels-Alder/Retro-Diels-Alder Reactions
Tejedor, David,Díaz-Díaz, Abián,Diana-Rivero, Raquel,Delgado-Hernández, Samuel,García-Tellado, Fernando
supporting information, p. 7987 - 7992 (2019/01/04)
The practical use of 2,2-dimethyl-2H-pyrans as electron-rich dienes in sequential Diels-Alder/retro-Diels-Alder (DA/rDA) domino processes to generate aromatic platforms has been demonstrated. Different polysubstituted alkyl 2-naphthoates have been synthesized by the DA/rDA reaction of benzynes and 2,2-dimethyl-2H-pyrans. The use of other activated alkynes allows the access of substituted alkyl benzoate derivatives.
Synthesis and Photochemistry of a New Photolabile Protecting Group for Propargylic Alcohols
Ma, Chi,Zhang, Youlai,Zhang, Huan,Li, Junru,Nishiyama, Yasuhiro,Tanimoto, Hiroki,Morimoto, Tsumoru,Kakiuchi, Kiyomi
supporting information, p. 560 - 564 (2017/03/11)
A new and efficient thiochromenone S,S-dioxide-based photolabile protecting group for propargylic alcohols is described. Robust protection reactions were developed through copper (II)-catalyzed substitution of propargylic alcohols. Subsequent photodeprote
Gold-Catalyzed [4+2]- and [3+3]-Annulations of Ynamides with 1-Yn-3-ols to Access Six-Membered Carbocycles and Oxacycles via Three Distinct Cyclizations
Giri, Sovan Sundar,Liu, Rai-Shung
supporting information, p. 3311 - 3318 (2017/09/13)
Three distinct strategies for catalytic annulations between ynamides and 1-yn-3-ols are described; the resulting carbo- and heterocycles were produced efficiently in one-pot operations using a gold catalyst. The chemoselectivities of these annulations are controlled by variations of the substituents of the ynamides and the 1-yn-3-ols. This reaction sequence involves initial alkoxylations of ynamides, followed by Claisen rearrangement of propargylic enol ethers, and ends with 6-endo-trig cyclizations of 1-allenyl-5-amide intermediates. Among these cascade annulations, the cyclizations of 5-allenyl-1-amides to yield 5,6-dihydro-2-pyranones and 6-alkylenecyclohex-2-ene-1-carboxamides are unprecedented in the literature. (Figure presented.).
Synthesis of Benzyl-, Allyl-, and Allenyl-boronates via Copper-Catalyzed Borylation of Alcohols
Mao, Lujia,Szabó, Kálmán J.,Marder, Todd B.
, p. 1204 - 1207 (2017/03/14)
Alcohols are among the most abundant and readily available organic feedstocks in industrial processes. The direct catalytic functionalization of sp3 C-O bonds of alcohols remains the main challenge in this field. Here, we report a copper-cataly
