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Synthesis 2007(10): 1587-1588  
DOI: 10.1055/s-2007-965953
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© Georg Thieme Verlag Stuttgart · New York

Practical Aspects in the Gram-Scale Synthesis of Chiral Diamino-Bithiophene ‘DAT2’ Ligand

Marco Bandini, Astrid Eichholzer, Simona Tommasi, Achille Umani-Ronchi*
Dipartimento di Chimica ‘G. Ciamician’, Università di Bologna, via Selmi 2, 40126 Bologna, Italy
Fax: +39(051)2099456; e-Mail: achille.umanironchi@unibo.it;
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Publication History

Received 24 January 2007
Publication Date:
28 February 2007 (online)

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Abstract

A gram-scale synthesis of the enantiomerically pure ligand DAT2 is described. The mild reaction conditions, operational simplicity, and satisfying isolated yield (68%) are some of the main features of this two-step reductive amination.

Key words

asymmetric catalysis - chiral ligands - amine - thiophene

    References and Notes

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  • 7b

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6

Bandini M., Tommasi S., Umani-Ronchi A., unpublished results.

10

When 1 was prepared on a large scale, the addition of an excess of cyclohexane-1,2-diamine during the reaction course was necessary in order to guarantee complete conversion.

11

The crude bis-imine intermediate was poorly soluble in MeOH and relatively large amounts of solvent were usually required for the reductive process.

12

Note, cooling the reaction to 0 °C during quenching would prevent the rapid evolution of gas.