Synthetic Study on 2,2′-(1,4-Phenylene)bis(3-alkyl-1H-inden-1-ones): The First Application of a Sodium Enolate as a ‘Protecting Group’ in the Grignard Reaction

Abstract

A new series of 2,2′-(1,4-phenylene)bis(3-substituted-1H-inden-1-ones) were prepared and their structures were established by ¹H and ¹³C NMR, IR, and HRMS spectroscopy. One molecular structure was further confirmed by single crystal X-ray crystallography. The synthetic mechanism was studied in detail. The key step involves the reaction of the Grignard reagent with the sodium enolate of 2,2′-(1,4-phenylene)bis[1H-indene-1,3(2H)-dione]. This is the first example of a sodium enolate being employed as the protecting reagent for a carbonyl group in the Grignard reaction.

Key words

2,2′-(1,4-phenylene)bis(3-alkyl-1H-inden-1-one) - enols - Grignard reactions - protecting groups - regioselectivity

References

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The data were deposited at the Cambridge Crystallographic Data Centre (No. CCDC 653343). Copies of this information can be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: [phone], e-mail: [e-mail] or http://www.ccdc.cam.ac.uk/conts/retrieving.html].

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Sheldrick, G. M., SHELXS97, Program for the Solution of Crystal Structures, University of Göttingen, Germany, 1997.

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SHELXL97, Program for the Refinement of Crystal Structure, University of Göttingen, Germany, 1997.