Highly efficient ortho-fluoro-dimeric cinchona-derived phase-transfer catalysts

Park, Hyeung‐geun; Jeong, Byeong‐Seon; Yoo, Mi‐Sook; Lee, Jeong-Hee; Park, Boon-saeng; Kim, Myoung Goo; Jew, Sang‐sup

doi:10.1016/s0040-4039(03)00687-7

Cited by 71 publications

(26 citation statements)

References 11 publications

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“…In Park’s subsequent development of catalyst CD-153b , a dozen of analogs ( CD-156b – 167b ) were obtained from differently 2- or 5- substituted -xylylene dibromides in 85–95 % yield [ 112 ]. In later works, a quinine analogue was also obtained [ 113 ].…”

Section: N1-qarternary Ammonium Saltsmentioning

confidence: 99%

“…The allylation of the 9-hydroxyl in the catalysts often significantly improved the enantioselectivity in the PTC transformation [ 111 ]. Study of analogues of CD-153 revealed that 2-fluorine atom in the xylylene linker as well as 10,11-hydrogenated alkaloid unit further improved the enantioselectivity [ 112 ]. A highly hindered trimer CD-196b provided high enantioselectivity at a cost of reactivity [ 128 ] The second generation Park’s catalyst DHCD-170b with 2,7-naphthyl link was one of the most efficient and enantioselective catalysts for the benzylation of glycine imine under PTC conditions providing 97 %ee at and 1 %mol loading [ 114 ].…”

Section: N1-qarternary Ammonium Saltsmentioning

confidence: 99%

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Dimeric Cinchona alkaloids

Boratyński

2015

Mol Divers

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Nature is full of dimeric alkaloids of various types from many plant families, some of them with interesting biological properties. However, dimeric Cinchona alkaloids were not isolated from any species but were products of designed partial chemical synthesis. Although the Cinchona bark is amongst the sources of oldest efficient medicines, the synthetic dimers found most use in the field of asymmetric synthesis. Prominent examples include the Sharpless dihydroxylation and aminohydroxylation ligands, and dimeric phase transfer catalysts. In this article the syntheses of Cinchona alkaloid dimers and oligomers are reviewed, and their structure and applications are outlined. Various synthetic routes exploit reactivity of the alkaloids at the central 9-hydroxyl group, quinuclidine, and quinoline rings, as well as 3-vinyl group. This availability of reactive sites, in combination with a plethora of linker molecules, contributes to the diversity of the products obtained.

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Section: N1-qarternary Ammonium Saltsmentioning

confidence: 99%

Section: N1-qarternary Ammonium Saltsmentioning

confidence: 99%

Dimeric Cinchona alkaloids

Boratyński

2015

Mol Divers

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“…Recent findings from our laboratory demonstrated, however, that the electronic effect of the N + -arylmethyl unit in the catalyst is also responsible for high enantioselectivity ).…”

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confidence: 93%

Evidence of the Electronic Factor for the Highly Enantioselective Catalytic Efficiency of Cinchona-Derived Phase-Transfer Catalysts

et al. 2005

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[structure: see text] The Cinchona alkaloid-derived quaternary ammonium salts containing 2'-N-oxypyridine and 2'-cyanobenzene moieties were prepared and evaluated as phase-transfer catalysts in the enantioselective alkylation of glycine imine ester 1. The N-oxypyridine and cyanobenzene moieties might play an important role to form a rigid conformation by coordinating with H(2)O via hydrogen bonding leading to high enantioselectivity (97 approximately >99% ee), which provides evidence of an electronic factor for the high enantioselective catalytic efficiency in phase-transfer alkylation.

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“…Although selected examples exist of highly enantioselective phase-transfer-catalyzed alkylations of glycinate Schiff bases with propargylic electrophiles, we were unsure of the prospects for obtaining suitable enantioselectivity in our case. In alkylations of the Schöllkopf reagent with TMS-propargylic electrophiles, Cook observed dramatic variations in diastereoselectivities (2.5:1 to 46:1) with respect to the leaving group.…”

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confidence: 93%

Catalytic Asymmetric Synthesis of the Central Tryptophan Residue of Celogentin C

Castle

Srikanth

2003

Org. Lett.

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[reaction: see text] Chiral phase-transfer catalyst 5 containing an electron-deficient trifluorobenzyl moiety promoted the alkylation of glycine derivative 6 with propargyl bromide 7a in good yield and excellent ee. The resulting propargyl glycine 8 was converted to 14, the central tryptophan residue of Celogentin C, in two steps, with the Pd-catalyzed heteroannulation as the key transformation. This method promises to be an efficient route for the preparation of tryptophan derivatives possessing substitution on the indole ring.

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Highly efficient ortho-fluoro-dimeric cinchona-derived phase-transfer catalysts

Cited by 71 publications

References 11 publications

Dimeric Cinchona alkaloids

Dimeric Cinchona alkaloids

Evidence of the Electronic Factor for the Highly Enantioselective Catalytic Efficiency of Cinchona-Derived Phase-Transfer Catalysts

Catalytic Asymmetric Synthesis of the Central Tryptophan Residue of Celogentin C

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