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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