“…Jacobsen pioneered a tertiary aminourea-catalyzed asymmetric iodolactonization using N -iodo-4-fluorophthalimide as the I + source and I 2 as an additive (Veitch and Jacobsen, 2010). In the subsequently developed metal-catalyzed and organocatalyzed asymmetric iodolactonization reactions, the combined use of an I + source (e.g., N -iodosuccinimide [NIS]) with I 2 is often effective to improve the results (Arai et al., 2015a, Arai et al., 2015b, Brindle et al., 2013, Dobish and Johnston, 2012, Fang et al., 2012, Filippova et al., 2014, Kwon et al., 2008, Lu et al., 2018, Mizar et al., 2014, Murai et al., 2014a, Murai et al., 2014b, Nakatsuji et al., 2014, Toda et al., 2014, Tripathi and Mukherjee, 2013; Tungen et al., 2012, Sakakura et al., 2007, Suresh et al., 2018, Wang et al., 2012). In 2014, we also reported a highly efficient catalytic asymmetric iodolactonization using a 3,3′-bis(aminoimino)binaphthol ligand ( L1 ) and Zn(OAc) 2 .…”
Section: Resultsmentioning
confidence: 99%
“…In 2014, we also reported a highly efficient catalytic asymmetric iodolactonization using a 3,3′-bis(aminoimino)binaphthol ligand ( L1 ) and Zn(OAc) 2 . Only 1 mol% of trinuclear Zn 3 (OAc) 4 -3,3′-bis(aminoimino)binaphthoxide ( tri-Zn ) was required to catalyze the asymmetric iodolactonization using NIS with the catalytic assistance of I 2 to afford the products at up to over 99% enantiomeric excess (ee) (Figure 2) (Arai et al., 2014, Arai et al., 2015a, Arai et al., 2015b). Figure 2Chiral Zn 3 (OAc) 4 -3,3′-bis(aminoimino)binaphthoxide ( tri-Zn ) Catalyst for Asymmetric Iodolactonization…”
SummaryCooperative activation using halogen bonding and hydrogen bonding works in metal-catalyzed asymmetric halolactonization. The Zn3(OAc)4-3,3′-bis(aminoimino)binaphthoxide (tri-Zn) complex catalyzes both asymmetric iodolactonization and bromolactonization. Carboxylic acid substrates are converted to zinc carboxylates on the tri-Zn complex, and the N-halosuccinimide (N-bromosuccinimide [NBS] or N-iodosuccinimide [NIS]) is activated by hydrogen bonding with the diamine unit of chiral ligand. Halolactonization is significantly enhanced by the addition of catalytic I2. Density functional theory calculations revealed that a catalytic amount of I2 mediates the alkene portion of the substrates and NIS to realize highly enantioselective iodolactonization. The tri-Zn catalyst activates both sides of the carboxylic acid and alkene moiety, so that asymmetric five-membered iodolactonization of prochiral diallyl acetic acids proceeded to afford the chiral γ-butyrolactones. In the total description of the catalytic cycle, iodolactonization using the NIS-I2 complex proceeds with the regeneration of I2, which enables the catalytic use of I2. The actual iodination reagent is I2 and not NIS.
“…Jacobsen pioneered a tertiary aminourea-catalyzed asymmetric iodolactonization using N -iodo-4-fluorophthalimide as the I + source and I 2 as an additive (Veitch and Jacobsen, 2010). In the subsequently developed metal-catalyzed and organocatalyzed asymmetric iodolactonization reactions, the combined use of an I + source (e.g., N -iodosuccinimide [NIS]) with I 2 is often effective to improve the results (Arai et al., 2015a, Arai et al., 2015b, Brindle et al., 2013, Dobish and Johnston, 2012, Fang et al., 2012, Filippova et al., 2014, Kwon et al., 2008, Lu et al., 2018, Mizar et al., 2014, Murai et al., 2014a, Murai et al., 2014b, Nakatsuji et al., 2014, Toda et al., 2014, Tripathi and Mukherjee, 2013; Tungen et al., 2012, Sakakura et al., 2007, Suresh et al., 2018, Wang et al., 2012). In 2014, we also reported a highly efficient catalytic asymmetric iodolactonization using a 3,3′-bis(aminoimino)binaphthol ligand ( L1 ) and Zn(OAc) 2 .…”
Section: Resultsmentioning
confidence: 99%
“…In 2014, we also reported a highly efficient catalytic asymmetric iodolactonization using a 3,3′-bis(aminoimino)binaphthol ligand ( L1 ) and Zn(OAc) 2 . Only 1 mol% of trinuclear Zn 3 (OAc) 4 -3,3′-bis(aminoimino)binaphthoxide ( tri-Zn ) was required to catalyze the asymmetric iodolactonization using NIS with the catalytic assistance of I 2 to afford the products at up to over 99% enantiomeric excess (ee) (Figure 2) (Arai et al., 2014, Arai et al., 2015a, Arai et al., 2015b). Figure 2Chiral Zn 3 (OAc) 4 -3,3′-bis(aminoimino)binaphthoxide ( tri-Zn ) Catalyst for Asymmetric Iodolactonization…”
SummaryCooperative activation using halogen bonding and hydrogen bonding works in metal-catalyzed asymmetric halolactonization. The Zn3(OAc)4-3,3′-bis(aminoimino)binaphthoxide (tri-Zn) complex catalyzes both asymmetric iodolactonization and bromolactonization. Carboxylic acid substrates are converted to zinc carboxylates on the tri-Zn complex, and the N-halosuccinimide (N-bromosuccinimide [NBS] or N-iodosuccinimide [NIS]) is activated by hydrogen bonding with the diamine unit of chiral ligand. Halolactonization is significantly enhanced by the addition of catalytic I2. Density functional theory calculations revealed that a catalytic amount of I2 mediates the alkene portion of the substrates and NIS to realize highly enantioselective iodolactonization. The tri-Zn catalyst activates both sides of the carboxylic acid and alkene moiety, so that asymmetric five-membered iodolactonization of prochiral diallyl acetic acids proceeded to afford the chiral γ-butyrolactones. In the total description of the catalytic cycle, iodolactonization using the NIS-I2 complex proceeds with the regeneration of I2, which enables the catalytic use of I2. The actual iodination reagent is I2 and not NIS.
“…More precise control of the microenvironment might be possible with chiral polymers containing chiral catalyst sites in their main‐chain structure instead of side‐chain immobilization. Recently, some main‐chain chiral polymers were synthesized and used as polymeric chiral ligands and catalysts …”
A chiral main‐chain polyamide containing an (R,R)‐1,2‐diphenylethylenediamine monotoluenesulfonamide (TsDPEN) repeating unit was prepared. Polycondensation of dicarboxylic acid dichloride with the chiral bisaniline of N‐tert‐butoxycarbonyl‐protected TsDPEN was successful and afforded a chiral polyamide with a TsDPEN repeating unit as the chiral ligand structure. Treatment of the main‐chain polymer chiral ligand with transition‐metal complexes, such as [IrCl2Cp*]2 (Cp*=η5‐pentamethylcyclopentadienyl), [RhCl2Cp*]2, and [RuCl2(p‐cymene)]2, afforded polymer chiral metal complexes. Asymmetric transfer hydrogenation of a cyclic sulfonamide was efficiently catalyzed by the chiral TsDPEN polymer–metal complex to give an optically active cyclic sulfonylamine with quantitative conversion and high enantioselectivity. The polymer catalyst was easily recovered from the reaction mixture and reused several times without any loss in catalytic activity or enantioselectivity.
“…In 2015, Arai et al described the synthesis of novel polymeric Zn 3 (OAc) 4 -3,3 0 -bis(aminoimino)binaphthoxide catalyst 281 through self-assembly of chiral 3,3 0 -diformylbinaphthol ligand 282, chiral tetramine ligand 283, and Zn(OAc) 2 (Scheme 96) [131]. This complex was found stable and efficient at only 2 mol % of catalyst loading to promote at À78 °C the asymmetric iodolactonization of a range of 5-substituted hex-5-enoic acids 284 into the corresponding chiral iodolactones 285.…”
This review collects the recent advances in the field of enantioselective zinc-catalyzed transformations, covering the literature since the beginning of 2015, illustrating the power of chiral green zinc catalysts to promote all types of reactions. A range of highly enantioselective reactions have been developed in the last six years, including cycloadditions, alkynylation/allylation reactions of carbonyl compounds and derivatives, additions of diorganozincs to carbonyl compounds and derivatives, Mannich reactions, (nitro)aldol reactions, other 1,2-nucleophilic additions to carbonyl compounds and derivatives, Michael additions, Friedel-Crafts reactions, reductions, a-functionalizations of carbonyl compounds, ringopening reactions, epoxidations, halolactonizations, domino/tandem reactions and miscellaneous reactions.
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