Marshall Propargylation

13 October, 2015 / by SK / in Reactions

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General Characteristics

In the Marshall propargylation, propargyl mesylates and aldehydes are reductively coupled to form a new carbon-carbon bond. The transfer of chirality from the mesylates allows for reliable construction of contiguous stereogenic centers. Reagents such as diethylzinc and indium(I) iodide are used as reducing agents. This reaction has been demonstrated to be useful in large scale settings.

General References

Marshall, J. A.; Adams, N. D. J. Org. Chem. 1998, 63, 3812. DOI: 10.1021/jo980623j
Marshall, J. A.; Adams, N. D. J. Org. Chem. 1999, 64, 5201. DOI: 10.1021/jo9823083
Marshall, J. A.; Grant, C. M. J. Org. Chem. 1999, 64, 696. DOI: 10.1021/jo982255p
Marshall, J. A.; Chobanian, H. R.; Yanik, M. M. Org. Lett. 2001, 3, 3369. DOI: 10.1021/ol016605x
Marshall, J. A.; Schaaf, G. M. J. Org. Chem. 2001, 66, 7825. DOI: 10.1021/jo015936k

Marshall, J. A. J. Org. Chem. 2007, 72, 8153. DOI: 10.1021/jo070787c
Ding, C.-H.; Hou, X.-L. Chem. Rev. 2011, 111, 1914. DOI: 10.1021/cr100284m

Reaction Mechanism

The mechanism involves generation of the chiral allenylzinc species involving redox cycle of the palladium catalyst. The allenyl zinc reacts with the aldehyde via a cyclic transition state with the transfer of chirality.

Examples

An example in the synthesis of lejjimalide B.^[1]

Total synthesis of ushikulide A.^[2]

Experimental Procedure
Experimental Tips
References

Chen, Q.; Schweitzer, D.; Kane, J.; Davisson, V. J.; Helquist,P. J. Org. Chem. 2011, 76, 5157. DOI: 10.1021/jo200514m
(a) Trost, B. M.; O’Boyle, B. M. J. Am. Chem. Soc. 2008, 130, 16190. (b) Trost, B. M.; O’Boyle, B. M.; Hund, D. J. Am. Chem. Soc. 2009, 131, 15061. DOI: 10.1021/ja906056v