2010
DOI: 10.1002/adsc.201000419
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Direct Asymmetric syn‐Aldol Reactions of Linear Aliphatic Ketones with Primary Amino Acid‐Derived Diamines

Abstract: Abstract:We have designed a novel class of chiral diamine organocatalysts based on natural primary amino acids that efficiently catalyze syn-selective aldol reactions of challenging linear ketones, such as 2-butanone, and aromatic aldehydes. In the presence of trifluoroacetic acid (TFA) as Brønsted acid and 2,4-dinitrophenol (DNP) as co-catalyst, synaldol products have been obtained with excellent enantioselectivities of up to > 99% ee.Keywords: aldol reaction; aliphatic ketones; chiral diamines; syn-diastereo… Show more

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Cited by 28 publications
(13 citation statements)
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“…With regard to the efficiency of the catalytic system, further optimization of the reaction conditions was conducted for 1b/nafion NR50 ( Table 2). In consistency with our previous findings for the homogeneous reaction with TFA, [18] the addition of 2,4-dinitrophenol (DNP) as a co-catalyst is beneficial to both the ac- [%] rr [b] b/l dr [b] syn/ anti ee [c] [%] H NMR (rr = regioisomer ratio, b/l = ratio of branched and linear products). [c] The ee of the major syn-isomer, determined by chiral GC.…”
Section: Resultssupporting
confidence: 82%
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“…With regard to the efficiency of the catalytic system, further optimization of the reaction conditions was conducted for 1b/nafion NR50 ( Table 2). In consistency with our previous findings for the homogeneous reaction with TFA, [18] the addition of 2,4-dinitrophenol (DNP) as a co-catalyst is beneficial to both the ac- [%] rr [b] b/l dr [b] syn/ anti ee [c] [%] H NMR (rr = regioisomer ratio, b/l = ratio of branched and linear products). [c] The ee of the major syn-isomer, determined by chiral GC.…”
Section: Resultssupporting
confidence: 82%
“…[18] With these catalysts, in the presence of TFA as Brønsted acid and DNP as co-catalyst, syn-aldol products have been obtained with excellent enantioselectivities. Hence, we selected diamines 1a and 1b (Scheme 2) for the noncovalent immobilization on organic and inorganic solid acids.…”
Section: Resultsmentioning
confidence: 98%
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“…10 Over the past decade, a number of similar syn-aldol reactions have been realized in laboratory (though, with a somewhat lower stereoselectivity) in the presence of properly designed primary aminocatalysts. Among them, O-protected serine or threonine amino acids, [11][12][13][14][15][16] their amides, 17 valine, 18 leucine, 19 iso-leucine 20 or tert-leucine derivatives 21 and some primary-tertiary 1,2-diamine organocatalysts [22][23][24][25][26][27] exhibited promising catalytic performance. However, unlike enzymes, these valuable catalysts could be used just once and until recently no information on their recovery and reuse in the catalytic process has been available.…”
Section: Introductionmentioning
confidence: 99%