652974-09-9Relevant articles and documents
An Enzymatic Platform for Primary Amination of 1-Aryl-2-alkyl Alkynes
Liu, Zhen,Qin, Zi-Yang,Zhu, Ledong,Athavale, Soumitra V.,Sengupta, Arkajyoti,Jia, Zhi-Jun,Garcia-Borràs, Marc,Houk,Arnold, Frances H.
supporting information, p. 80 - 85 (2022/01/08)
Propargyl amines are versatile synthetic intermediates with numerous applications in the pharmaceutical industry. An attractive strategy for efficient preparation of these compounds is nitrene propargylic C(sp3)-H insertion. However, achieving this reacti
Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis
Geyer, Andrea M.,Wiedner, Eric S.,Gary, J. Brannon,Gdula, Robyn L.,Kuhlmann, Nicola C.,Johnson, Marc J. A.,Dunietz, Barry D.,Kampf, Jeff W.
scheme or table, p. 8984 - 8999 (2009/02/03)
The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.
Highly Active Trialkoxymolybdenum(VI) Alkylidyne Catalysts Synthesized by A Reductive Recycle Strategy
Zhang, Wei,Kraft, Stefan,Moore, Jeffrey S.
, p. 329 - 335 (2007/10/03)
A systematic study of alkyne metathesis catalyzed by trialkoxymolybdenum(VI) alkylidyne complexes is reported, in which substrate functional groups, alkynyl substituents, and catalyst ligands are varied. Sterically hindered trisamidomolybdenum(VI) propylidyne complex 5 was prepared conveniently through a previously communicated reductive recycle strategy. Alcoholysis of 5 with various phenols/alcohols provides a set of active catalysts for alkyne metathesis at room temperature, among which the catalyst with p-nitrophenol as ligand shows the highest catalytic activity and is compatible with a variety of functional groups and solvents. A key finding that enabled the use of highly active molybdenum(VI) catalysts is replacement of the commonly used propynyl substituents on the starting alkyne substrates with butynyl groups. Under reduced pressure using 1,2,4-trichlorobenzene as an involatile solvent, the alkyne metathesis of butynyl substituted compounds proceeds well at 30 °C providing high yields (83%-97%) of dimers. Rationalization of the special role played by butynyl substrates is discussed.
