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- 1 (2009-01-21 (水) 18:12:33)
In the course of our study on the synthetic application of cyanoboranes, we found interesting reactivity of bis(dialkylamino)cyanoboranes toward carbonyl compounds. In 1:1 reaction of the cyanoboranes with aldehydes at room temperature, α-dialkylamino nitriles were obtained in high yields [Ref. 1].
#ref(Graphics for Reserch/aminocyanation80.jpg,center)
We designed aminoboranes bearing bulky diisopropyl groups on the boron atom. The aminoboranes served as a universal iminium ion generator, allowing use of free '''sec'''-amines in the Mannich-type reaction as the source of the amino group through facile amino group exchange on the boron atom [Ref. 2].
#ref(Graphics for Reserch/Mannich-type reaction80.jpg,center)
The reaction protocol could be extended to other amination reactions, such as reductive amination [Ref. 3] and Ugi reactions [Ref. 4].
#ref(Graphics for Reserch/reductive amination80.jpg,center)
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#ref(Graphics for Reserch/Ugi reaction80.jpg,center)
More recently, we found that diphenylborinic acid derivatives serve as “catalytic” iminium ion generators in the Mannich-type reactions [Ref. 5].
#ref(Graphics for Reserch/catalytic iminium ion generator80.jpg,center)
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**References
-Ref. 1
--Bis(dialkylamino)cyanoboranes: highly efficient reagents for the Strecker-type aminative cyanation of aldehydes and ketones. M. Suginome, A. Yamamoto, Y. Ito, '''Chem. Comm.''' ''2002'', 1392-1393, [[10.1039/b203645b>http://dx.doi.org/10.1039/b203645b]]
--New Look at Boron Enolate Chemistry: Aminative C–C Bond Formation Using Diaminoboron Enolate with Aldehyde M. Suginome, L. Uhelin, A. Yamamoto, M. Murakami, '''Org. Lett'''. ''2004'', 6, 1167-1169, [[10.1021/ol0497436>http://dx.doi.org/10.1021/ol0497436]]
-Ref. 2
--Aminoboranes as "Compatible" Iminium Ion Generators in Aminative C-C Bond Formations M. Suginome, L. Uhelin, M. Murakami, '''J. Am. Chem. Soc.''' 2004, 126, 13196-13197, [[10.1021/ja045827y>http://dx.doi.org/10.1021/ja045827y]]
--Aminoboranes as New Iminium Ion Generators in Amination Reactions M. Suginome, '''Pure Appl. Chem.''' ''2006'', 78, 1377-1387, [[10.1351/pac200678071377>http://dx.doi.org/10.1351/pac200678071377]]
-Ref. 3
--Reductive Amination of Aldehydes Using Aminoboranes as Iminium Ion Generators M. Suginome, Y. Tanaka, and T. Hasui, '''Synlett''' ''2006'', 1047–1050, [[10.1055/s-2006-939070>http://dx.doi.org/10.1055/s-2006-939070]]
-Ref. 4
--Acid-free, Aminoborane-mediated Ugi-type Reaction Leading to General Utilization of Secondary Amines Y. Tanaka, Tomoaki Hasui, M. Suginome, '''Org. Lett.''' ''2007'', 9, 4407-4410, [[10.1021/ol701570c>http://dx.doi.org/10.1021/ol701570c]]
-Ref. 5
--Diarylborinic Acid Derivatives as a Catalytic Iminium Ion Generator in the Mannich-type Reaction Using sec-Amines, Aldehydes, and Ketene Silyl Acetals Y. Tanaka, T. Hasui, M. Suginome, '''Synlett''', ''2008'', 1239–1242, [[10.1055/s-2008-1072724>http://dx.doi.org/10.1055/s-2008-1072724]]
