Hydrogenation of 1,2-indanedione over heterogeneous cinchonidine-modified platinum catalysts
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Catalysis Letters, Vol. 117, Nos. 3–4, September 2007 ( 2007) DOI: 10.1007/s10562-007-9123-8
Hydrogenation of 1,2-indanedione over heterogeneous cinchonidine-modified platinum catalysts Igor Busygin,a Michael Rosenholm,a Esa Toukoniitty,b Dmitry Yu. Murzin,b,* and Reko Leinoa,* Laboratory of Organic Chemistry, A˚bo Akademi University, A˚bo, Finland Laboratory of Industrial Chemistry, A˚bo Akademi University, A˚bo, Finland
a b
Received 10 April 2007; accepted 10 April 2007
Hydrogenation of the prochiral diketone, 1,2-indanedione was for the first time investigated using cinchonidine-modified Pt/ Al2O3 as a catalyst. The influence of the reaction parameters on catalyst activity, regio- and enantioselectivity was studied revealing fully regioselective hydrogenation of the C(2)-keto group. Enantioselectivities of the (R)- versus (S)-2-hydroxy-1-indanone varied from low to moderate in favor of the (R)-enantiomer. A systematic study of enantioselective hydrogenation of 1,2-indanedione – a new substrate for chirally modified heterogeneous catalysts – over cinchonidine modified Pt/Al2O3 is presented. The influence of the reaction parameters on activity, regio- and enantioselectivity was studied.
O
H2, Pt/Al2O3, cinchonidine, toluene O
10 bar, 15 °C
1,2-Indanedione
O R
OH
up to 35 % ee
KEY WORDS: 1,2-indanedione; 2-hydroxy-1-indanone; heterogeneous hydrogenation; cinchonidine.
1. Introduction Chiral 1-amino-2-indanols are important building blocks utilized in the synthesis of several biologically active compounds (e.g., HIV protease inhibitors) [1]. They also find applications in asymmetric catalysis [2] as chiral auxiliaries and as chiral resolving agents [3,4]. Therefore, the simple and inexpensive synthesis of these compounds would be highly desirable. Most of the known synthesis protocols involve the use of enzyme catalysis [5] or homogeneous catalysts [6], which often are both expensive and difficult to separate from the reaction mixture and to recover. Heterogeneous catalysis in turn is a method free from these disadvantages. Previously, we have investigated the enantioselective hydrogenation of 1-phenyl-1,2-propanedione (PPD) over chirally modified heterogeneous catalysts [7]. Since 1-amino-2-indanols are readily available from 2-hydroxy-1-indanone [8a] or 1,2-indandiols [8b] by the *To whom correspondence should be addressed. E-mails: reko.leino@abo.fi; dmurzin@abo.fi
Ritter process, the chiral 1,2-indandiols themselves are important building blocks. The cyclic 1,2-indanedione is a rigid analogue of PPD and could thus also provide additional mechanistic insights into the hydrogenation of its linear congener. Here, we present our results on the hydrogenation of 1,2-indanedione over a cinchonidine modified Pt/Al2O3 catalyst.
2. Experimental part 2.1. Synthesis of the reactants and reference compounds 1,2-Indanedione [9a,10a], racemic 2-hydroxy-1-indanone [10] and 1-hydroxy-2-indanone [11], (1R,2S)-indandiol [4], (1S,2S)-indandiol [9b], and (S)-2-hydroxy-1-indanone [8a,9b,12] were prepared according to literature pro
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