- Synthesis of Amide Enol Carbamates and Carbonates through Cu(OTf)2-Catalyzed Reactions of Ynamides with t-Butyl Carbamates/Carbonates
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A highly regioselective approach to access amide enol carbamates and carbonates 5a-5c′, 7a-7h, and 9 was developed through Cu(OTf)2-catalyzed reactions of ynamides 4 with t-butyl carbamates 2 and 8 and t-butyl carbonates 6. Moreover, this strategy was successfully applied to generate amide enol carbamates 11a-11s and 14a-14f from imides 10 and 13 with ynamides through an N-Boc cleavage-addition ring-opening process. A range of substituents was amenable to this transformation, and the desired amide enol carbamates and carbonates were obtained in moderate to good yields.
- Han, Pan,Mao, Zhuo-Ya,Li, Ming,Si, Chang-Mei,Wei, Bang-Guo,Lin, Guo-Qiang
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p. 4740 - 4752
(2020/04/30)
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- Sustainable Palladium-Catalyzed Tsuji-Trost Reactions Enabled by Aqueous Micellar Catalysis
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Palladium-catalyzed allylic substitution, or "Tsuji-Trost"reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.
- Braga, Felipe C.,Gallou, Fabrice,Lee, Nicholas R.,Lippincott, Daniel J.,Lipshutz, Bruce H.,Moghadam, Farbod A.,Zhu, Bingchun
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supporting information
(2020/07/15)
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- Asymmetric Synthesis of α-Quaternary γ-Lactams through Palladium-Catalyzed Asymmetric Allylic Alkylation
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The synthesis of chiral unsaturated γ-lactams is reported featuring a highly enantioselective palladium-catalyzed asymmetric allylic alkylation of α, γ-disubstituted 2-silyloxypyrroles. This method allows a straightforward access to optically active γ-lactams bearing an α-quaternary stereogenic center in high yields (up to 93%), high regioselectivities (up to >20:1), and excellent enantioselectivities (up to 95% ee). To further demonstrate the synthetic utility of the method, the resulting allylated products were converted to various versatile chiral building blocks, such as pyrrolidines and pyrrolidinones.
- Song, Tao,Arseniyadis, Stellios,Cossy, Janine
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supporting information
p. 603 - 607
(2019/02/28)
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- Enantioselective iridium catalyzed α-alkylation of azlactones by a tandem asymmetric allylic alkylation/aza-Cope rearrangement
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The development of an iridium catalyzed enantioselective α-alkylation of azlactones has been described. The reaction provides rapid access to a wide range of enantio-enriched quaternary carbon center allylated 2,4-diaryloxazol-5(2H)-ones in excellent yiel
- Bai, Xue-Dan,Zhang, Qing-Feng,He, Ying
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supporting information
p. 5547 - 5550
(2019/05/21)
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- Asymmetric Dearomatization/Cyclization Enables Access to Polycyclic Chemotypes
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Enantioenriched, polycyclic compounds were obtained from a simple acylphloroglucinol scaffold. Highly enantioselective dearomatization was accomplished using a Trost ligand–palladium(0) complex. A computational DFT model was developed to rationalize observed enantioselectivities and revealed a key reactant-ligand hydrogen bonding interaction. Dearomatized products were used in visible light-mediated photocycloadditions and oxidative free radical cyclizations to obtain novel polycyclic chemotypes including tricyclo[4.3.1.01,4]decan-10-ones, bicyclo[3.2.1]octan-8-ones and highly substituted cycloheptanones.
- Hayashi, Mikayo,Brown, Lauren E.,Porco, John A.
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supporting information
p. 4800 - 4804
(2016/10/13)
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- Iridium-catalyzed allyl-allyl cross-coupling of allylic carbonates with (E)-1,3-diarylpropenes
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An efficient Ir-catalyzed allyl-allyl cross-coupling reaction of allylic carbonates with (E)-1,3-diarylpropenes was developed to form linear allylated products, 1,5-dienes, regioselectively in excellent yields and with high turnover numbers (up to 2000 S/
- Yuan, Qianjia,Yao, Kun,Liu, Delong,Zhang, Wanbin
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supporting information
p. 11834 - 11836
(2015/07/15)
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- Branched/linear selectivity in palladium-catalyzed allyl-allyl cross-couplings: the role of ligands
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Abstract While Pd-catalyzed allyl-allyl cross-couplings in the presence of small-bite-angle bidentate ligands reliably furnish the branched regioisomer with high levels of selectivity, cross-couplings in the presence of large-bite-angle bidentate ligands
- Ardolino, Michael J.,Morken, James P.
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supporting information
p. 6409 - 6413
(2015/08/18)
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- Congested C-C bonds by Pd-catalyzed enantioselective allyl-allyl cross-coupling, a mechanism-guided solution
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Under the influence of a chiral bidentate diphosphine ligand, the Pd-catalyzed asymmetric cross-coupling of allylboron reagents and allylic electrophiles establishes 1,5-dienes with adjacent stereocenters in high regio-and stereoselectivity. A mechanistic study of the coupling utilizing reaction calorimetry and density functional theory analysis suggests that the reaction operates through an inner-sphere 3,3′-reductive elimination pathway, which is both rate-defining and stereodefining. Coupled with optimized reaction conditions, this mechanistic detail is used to expand the scope of allyl-allyl couplings to allow the generation of 1,5-dienes with tertiary centers adjacent to quaternary centers as well as a unique set of cyclic structures.
- Ardolino, Michael J.,Morken, James P.
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supporting information
p. 7092 - 7100
(2014/06/09)
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- Mixed metal MgO-ZrO2 nanoparticle-catalyzed O-tert-Boc protection of alcohols and phenols under solvent-free conditions
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An environmentally benign method for O-tert-Boc protection of alcohols and phenols catalyzed by MgO-ZrO2 nanoparticles under solvent-free conditions is described. A variety of phenols, alcohols (aliphatic and aromatic) were converted to corresponding O-tert-Boc products in good to excellent yield (50-95%). The present protocol is expedient, simple, and efficient under solvent-free conditions. The MgO-ZrO2 Nps are easily prepared from inexpensive precursors, and are reusable, recyclable and chemoselective. Copyright 2012 John Wiley & Sons, Ltd. Copyright
- Gawande, Manoj B.,Shelke, Sharad N.,Branco, Paula S.,Rathi, Anuj,Pandey, Rajesh K.
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experimental part
p. 395 - 400
(2012/09/25)
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- Iridium-catalyzed, regio- and enantioselective allylic substitution with aromatic and aliphatic sulfinates
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"Chemical Equation Presented" The iridium-catalyzed allylation of sodium sulfinate to form branched allylic sulfones is reported. The reactions between various sodium sulfinates and achiral allylic carbonates occur in good yields, with high selectivity fo
- Ueda, Mitsuhiro,Hartwig, John F.
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supporting information; experimental part
p. 92 - 94
(2010/03/04)
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- Pd-catalyzed enantioselective allyl-allyl cross-coupling
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The Pd-catalyzed cross-coupling of allylic carbonates and allylB(pin) is described. The regioselectivity of this reaction is sensitive to the bite angle of the ligand, with small-bite-angle ligands favoring the branched substitution product. This mode of
- Zhang, Ping,Brozek, Laura A.,Morken, James P.
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supporting information; experimental part
p. 10686 - 10688
(2010/11/04)
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- Direct, intermodular, enantioselective, iridium-catalyzed allylation of carbamates to form carbamate-protected, branched allylic amines
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The direct reaction between carbamates and achiral allylic carbonates to form branched, conveniently protected primary allylic amines with high regioseiectivity and enantioselectivity Is reported. This process occurs without base or with 0.5 equiv K3PO4 In the presence of a metalacyclic iridium catalyst containing a labile ethylene ligand. The reactions of aryl-, heteroaryl-, and alkyl-substituted allylic carbonates with BocNH 2, FmocNH2, CbZNH2, TrocNH2, TeocNH2, and 2-oxazolidinone occur In good yields, with high selectivity for the branched isomer and high enantioselectivities (98% average ee).
- Weix, Daniel J.,Markovic, Dean,Ueda, Mitsuhiro,Hartwig, John F.
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supporting information; experimental part
p. 2944 - 2947
(2009/12/05)
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- Iridium-catalyzed regio- and enantioselective N-allylation of indoles
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Iridium is blind to C: Highly regio- and enantioselective, iridium-catalyzed N-allylations of indoles, which complement the more common reactivity of indoles as carbon nucleophiles, have been developed (see scheme). These reactions form highly enantioenri
- Stanley, Levi M.,Hartwig, John F.
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supporting information; body text
p. 7841 - 7844
(2010/04/02)
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- Nickel-catalyzed allylation of allyl carbonates with homoallyl alcohols via retro-allylation providing 1,5-hexadienes
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A highly efficient and mild method for the synthesis of 1,5-hexadienes, nickel-catalyzed reactions of Boc-protected allyl alcohols with homoallyl alcohols, has been developed. Nickel-mediated retro-allylation allows for the use of homoallyl alcohols as allylmetal equivalents in the synthesis of 1,5-hexadienes.2008 American Chemical Society.
- Sumida, Yuto,Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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supporting information; body text
p. 1629 - 1632
(2009/04/10)
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- Di-tert-butyl dicarbonate and 4-(dimethylamino)pyridine revisited. Their reactions with amines and alcohols
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The reaction of BOC2O in the presence and absence of DMAP was examined with some amines, alcohols, diols, amino alcohols, and aminothiols. Often, unusual products were observed depending on the ratio of reagents, reaction time, polarity of solvent, pK(a) of alcohols, or type of amine (primary or secondary). In reactions of aliphatic alcohols with BOC2O/DMAP, we isolated for the first time carbonic-carbonic anhydride intermediates; this helps explain the formation of symmetrical carbonates in addition to the O-BOC products. In the case of secondary amines, we succeeded to isolate unstable carbamic-carbonic anhydride intermediates that in the presence of DMAP led to the final N-BOC product. The effect of N-methylimidazole in place of DMAP was also examined.
- Basel, Yochai,Hassner, Alfred
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p. 6368 - 6380
(2007/10/03)
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