1 3
Topics in Current Chemistry (2019) 377:23
In 2006, Inanaga’s group identified the perfluorinated phosphate complex Sc[(R)L19] 3 as a chiral catalyst in the fluorination reaction of β-ketoesters 125 with electrophilic 1-fluoropyridinium triflate 126 (Scheme 33) [136]. The presence of fluorine atom in Sc[(R)-L19] 3 is critical and causes a stronger Lewis acidity than its
analogous Sc[(R)-L4] 3 . Under simple conditions, both cyclic and acyclic dicarbonyl
substrates 125 were applicable for the asymmetric fluorination to provide 127 with
high enantioselectivities (up to 88% ee).
In 2013, Luo and co-workers [61] published a highly selective [4 + 2] cycloaddition of olefins 47 with β, γ-unsaturated α-ketoesters 10 (Scheme 34). Significant
binary catalysis with Sc(BArF) 3 [BArF = [3,5-(CF 3 ) 2 C 6 H 3 ] 4 B] and chiral calcium
phosphate proved to be effective for the synthesis of endo-cycloaddition products 128 in excellent diastereoselectivity (Scheme 34). Based on the literature and
experimental observations, a bidentate activation (129) between ketoester 10 and
Scheme 32 Scandium phosphate-catalyzed hetero-Diels–Alder reaction and conjugate addition
Scheme 33 Asymmetric fluorination of β-keto esters with 1-fluoropyridinium triflate
Reprinted from the journal
177
Topics in Current Chemistry (2019) 377:23
In 2006, Inanaga’s group identified the perfluorinated phosphate complex Sc[(R)L19] 3 as a chiral catalyst in the fluorination reaction of β-ketoesters 125 with electrophilic 1-fluoropyridinium triflate 126 (Scheme 33) [136]. The presence of fluorine atom in Sc[(R)-L19] 3 is critical and causes a stronger Lewis acidity than its
analogous Sc[(R)-L4] 3 . Under simple conditions, both cyclic and acyclic dicarbonyl
substrates 125 were applicable for the asymmetric fluorination to provide 127 with
high enantioselectivities (up to 88% ee).
In 2013, Luo and co-workers [61] published a highly selective [4 + 2] cycloaddition of olefins 47 with β, γ-unsaturated α-ketoesters 10 (Scheme 34). Significant
binary catalysis with Sc(BArF) 3 [BArF = [3,5-(CF 3 ) 2 C 6 H 3 ] 4 B] and chiral calcium
phosphate proved to be effective for the synthesis of endo-cycloaddition products 128 in excellent diastereoselectivity (Scheme 34). Based on the literature and
experimental observations, a bidentate activation (129) between ketoester 10 and
Scheme 32 Scandium phosphate-catalyzed hetero-Diels–Alder reaction and conjugate addition
Scheme 33 Asymmetric fluorination of β-keto esters with 1-fluoropyridinium triflate
Reprinted from the journal
177