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Synfacts 2020; 16(02): 0184
DOI: 10.1055/s-0039-1691468
Metals in Synthesis
© Georg Thieme Verlag Stuttgart · New York

Homo-aldol Reactions of Unsaturated Carbamates

Contributor(s):
Paul Knochel
,
Alexander Kremsmair
Hoppe D. * Zschage O. Westfälische Wilhelms-Universität Münster, Germany
Asymmetric Homoaldol Reaction by Enantioselective Lithiation of a Prochiral 2-Butenyl Carbamate.

Angew. Chem. Int. Ed. 1989;
28: 69-71
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Further Information

Publication History

Publication Date:
21 January 2020 (online)

 
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Key words

enantioselectivity - lithium - titanium

Significance

In 1989, Hoppe and co-workers reported the highly stereoselective homoaldol reaction of lithiated (E)-but-2-en-1-yl diisopropylcarbamates with carbonyl electrophiles leading to optically pure enol carbamates in high yields and good to excellent optical purity. After further transformation of the chiral products, the authors were able to prepare diastereomerically pure γ-lactones in high yields.


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Comment

In the decades since its discovery, the enantioselective synthesis with lithium/(–)-sparteine carbanion pairs has attracted considerable interest within the scientific community and has been applied in numerous natural product syntheses.


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Review

D. Hoppe, T. Hense ­Angew. Chem. Int. Ed. 1997, 36, 2282–2316.


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