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A Valuable Addition to Your Bidentate Ligand System

The success of enantioselective catalysis in organic synthesis is largely based on the development of chiral phosphine ligands.  For this reason, phosphorus-based ligands are of great interest and a wide range of these products are available at Strem.  As a phospha-alkene ligand, (S)-(+)-(3,5-Dioxa-4-phosphacyclohepta[2,1-a;3,4-a']dinaphthalen-4-yl)-5H-dibenz[b,f]azepine (15-1227) constitutes a valuable addition to the tool box of bidentate ligand systems used in catalysis.

This chiral dibenzazepine-based phospha-alkene ligand, as copper and rhodium complexes, catalyzes the asymmetric 1,4 additions of arylboronic acids to enones.^1,2  At 80°C turnover numbers of up to 61 and enantiomeric excesses of up to 92%, were observed.

In the first example, the iridium complex of 15-1227 catalyzes the synthesis of primary allylic amines from allylic alcohols, of a direct iridium-catalyzed synthesis of primary allylic amines.³  This fully stereodivergent, dual catalytic α-allylation of linear aldehydes has recently been published using 15-1227 in the direct iridium-catalyzed substitution of racemic allylic alcohols with enamines. 

The α-allylation reaction was highlighted in a recent enantioselective synthesis of the antidepressant (-)-paroxetine.⁴   Publications on thenantioselective allylic etherification⁵and thioetherification⁶ using 15-1227 and iridium can also be found within the references below.

Direct, enantioselective iridium-catalyzed allylic amination of racemic allylic alcohols¹⁰ features a method which includes the preparation of amine products through the displacement of alcohols.  There is no need for prior activation, resorting to high dilutions, or the use of protected amines.  15-1227 is also highly effective as the chiral phosphorus amidite-olefin ligand for the palladium-catalyzed asymmetric allylic alkylations of indoles,⁷ enantio- and diastereodivergent dual catalysis for  α-allylation of branched aldehydes,⁸  and  asymmetric intramolecular hydroacylation as a rhodium complex.⁹   In addition, 15-1227 was recently used in the total synthesis of (+)-Asperolide C.¹¹

References:

1.    Organometallics 2008, 27, 6605.
2.    Organometallics 2010, 29, 2503.
3.    Angew. Chem. Int. Ed., 2007, 46, 3139.
4.    Angew. Chem. Int. Ed., 2013, 52, 12166.
5.    Angew. Chem. Int. Ed., 2011, 50, 5568.
6.    Angew. Chem. Int. Ed., 2012, 51, 8652.
7.    Org. Biomol. Chem., 2011, 9, 5369.
8.    Science (Washington, DC, United States) 2013, 340, 1065.
9.    Angew. Chem. Int. Ed., 2011, 50, 10670.
10.    Angew. Chem. Int. Ed., 2012, 51, 3470.
11.    J. Am. Chem. Soc., 2014, 136, 3020.

Products mentioned in this blog:

15-1227: (S)-(+)-(3,5-Dioxa-4-phosphacyclohepta[2,1-a;3,3-a’]dinaphthalen-4-yl)-5H-dibenz[b,f]azepine, min. 97% [942939-38-0]

Please follow the link for a complete publication of our current Phosphorus Ligands and Compounds