Download - Ashok Selective hydroformylation
Facile Regio and Stereoselective Hydrometalation of Alkynes with a
Combination of Carboxylic Acids and Group 10 Transition Metal
Complexes: Selective Hydrogenation of Alkynes with Formic Acid
Presented by
Ashok Jangid
School of chemical sciences
Central university of Gujarat
Outline
Introduction
Objective
Reaction path
Importance of the study
Conclusion
Introduction
Combination of Pd(0) complex with carboxylic acid is an efficient catalyst for various transformations of alkynes
Cyclization of enynes
Hydrocarbonylation
Hydroarylation
Cyclo isomerization of alkynes
For these reactions mechanistic aspects were not clear and a direct proof of formation of alkenyl Pd intermediate is not clear
Conversion of alkynes to alkens can be achieved by hydrogenation
Lindlars catalyst
Raney nikel
Pd/C
These methods are often suffers from the lack of chemo and stereoselectivity
Objectives
Facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex
Selective Hydrogenation of Alkynes with Formic Acid
Reaction path Scheme 1:
Hydrometalation proceeds via a reaction of an alkyne coordinate metal (0) complex with the acid
Scheme 2 Reaction Path to Complex alkenyl Pt Complex
Scheme 3 Selective Hydrogenation of Alkynes with Formic Acid
Importance of the study
Isolation of alkenyl Pd intermediate
Characteristic property of group 10 transition metals
By using formic acid selective hydrogenation of alkynes
Conclusion
Facile hydrometalation of alkynes with a combination of carboxylic acids and group 10 transition
metal complexes M(PEt3)4 (M = Ni, Pd, Pt) to afford fully characterized alkenyl metals was
revealed. This finding provides direct proof for the reaction mechanism involving the combination
of carboxylic acid and zerovalent palladium catalyst. On the basis of this finding, an unprecedented
controllable hydrogenation of alkynes with formic acid was developed to selectively produce cis-,
trans-alkenes and alkanes by slightly tuning the conditions.
References
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Kalck, P.; Urrutigoiy, M.; Dechy-Cabaret, O. Top. Organomet. Chem. 2006, 18, 97.
C. H.; Jung, H. H.; Kim, K. S. Angew. Chem., Int. Ed. 2003, 42, 805.
B. M.; Brieden, W.; Baringhaus, K. H. Angew. Chem., Int. Ed. 1992, 31, 1335.
Yamamoto, Y.; Radhakrishnan, U. Chem. Soc. Rev. 1999, 28, 199.
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