- Transition metal mediated surface modification of porous silicon
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Porous silicon has received considerable attention lately due to its unique optical properties and use in sensor applications. The utility of this material can be further advanced with the aid of new surface chemical modification methods. Here we describe two transition metal mediated reactions that allow for the mild and chemoselective functionalization of porous silicon. The first method utilizes rhodium carbene chemistry to modify porous silicon surfaces with esters and amides. The second technique exploits a pt-based Karstedt's catalyst to affect the hydrosilylation of porous silicon with alkenes. The mildness and selectivity of the hydrosilylation is highlighted by modification of n-type porous silicon matrix with an 8-residue cyclic peptide.
- Saghatelian, Alan,Buriak, Jillian,Lin, Victor S.Y,Ghadiri, M. Reza
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- Conversion of azides into diazo compounds in water
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Diazo compounds are in widespread use in synthetic organic chemistry but have untapped potential in chemical biology. We report on the design and optimization of a phosphinoester that mediates the efficient conversion of azides into diazo compounds in phosphate buffer at neutral pH and room temperature. High yields are maintained in the presence of common nucleophilic or electrophilic functional groups, and reaction progress can be monitored by colorimetry. As azido groups are easy to install and maintain in biopolymers or their ligands, this new mode of azide reactivity could have substantial utility in chemical biology.
- Chou, Ho-Hsuan,Raines, Ronald T.
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- 1,3-Dipolar Cycloaddition with Diazo Groups: Noncovalent Interactions Overwhelm Strain
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Like azides, diazoacetamides undergo 1,3-dipolar cycloadditions with oxanorbornadienes (OND) in a reaction that is accelerated by the relief of strain in the transition state. The cycloaddition of a diazoacetamide with unstrained ethyl 4,4,4-trifluoro-2-butynoate is, however, 35-fold faster than with the analogous OND because of favorable interactions with the fluoro groups. Its rate constant (k = 0.53 M-1 s-1 in methanol) is comparable to those of strain-promoted azide-cyclooctyne cycloadditions.
- Gold, Brian,Aronoff, Matthew R.,Raines, Ronald T.
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- 1,3-Dipolar Cycloadditions of Diazo Compounds in the Presence of Azides
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The diazo group has untapped utility in chemical biology. The tolerance of stabilized diazo groups to cellular metabolism is comparable to that of azido groups. However, chemoselectivity has been elusive, as both groups undergo 1,3-dipolar cycloadditions with strained alkynes. Removing strain and tuning dipolarophile electronics yields diazo group selective 1,3-dipolar cycloadditions that can be performed in the presence of an azido group. For example, diazoacetamide but not its azido congener react with dehydroalanine residues, as in the natural product nisin.
- Aronoff, Matthew R.,Gold, Brian,Raines, Ronald T.
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- N-transfer reagent and method for preparing the same and its application
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Provided are a novel N-transfer reagent and a method for preparing the same and its application. The N-transfer reagent is represented by the following Formula (I): The various novel N-transfer reagents of the present invention can be quickly prepared by employing different nitrobenzene precursors. The N-transfer reagents can directly convert a variety of amino compounds into diazo compounds under mild conditions. Particularly, the N-transfer reagents can facilitate the synthesis of the diazo compounds. The application of synthesizing diazo compounds of the present invention can greatly decrease the difficulty in operation, increase the safety during experiments, reduce the cost of production and the environmental pollution, and enhance the industrial value of diazo compounds.
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Page/Page column 26-29; 59-60; 69-70
(2021/06/25)
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- NovelN-transfer reagent for converting α-amino acid derivatives to α-diazo compounds
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A novel universalN-transfer reagent for direct and effective transformation of α-amino ketones, acetamides, and esters to the corresponding α-diazo products under mild basic conditions has been developed. This one-step synthetic approach not only allows for generation of α-substituted-α-diazo carbonyl compounds from α-amino acid derivatives but also permits preparation of α-diazo dipeptides fromN-terminal dipeptides (32 examples, up to 91%).
- Lu, Guan-Han,Huang, Tzu-Chia,Hsueh, Hsiao-Chin,Yang, Shin-Cherng,Cho, Ting-Wei,Chou, Ho-Hsuan
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supporting information
p. 4839 - 4842
(2021/05/25)
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- Catalytic Asymmetric Epoxidation of Aldehydes with Two VANOL-Derived Chiral Borate Catalysts
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A highly diastereo- and enantioselective method for the epoxidation of aldehydes with α-diazoacetamides has been developed with two different borate ester catalysts of VANOL. Both catalytic systems are general for aromatic, aliphatic, and acetylenic aldehydes, giving high yields and inductions for nearly all cases. One borate ester catalyst has two molecules of VANOL and the other only one VANOL. Catalysts generated from BINOL and VAPOL are ineffective catalysts. An application is shown for access to the side-chain of taxol.
- Gupta, Anil K.,Yin, Xiaopeng,Mukherjee, Munmun,Desai, Aman A.,Mohammadlou, Aliakbar,Jurewicz, Kelsee,Wulff, William D.
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supporting information
p. 3361 - 3367
(2019/02/16)
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- A highly enantioselective Darzens reaction between diazoacetamides and aldehydes catalyzed by a (+)-pinanediol-Ti(OiPr)4 system
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A highly efficient enantioselective Darzens reaction of aldehydes with diazoacetamides catalyzed by a (+)-pinanediol-Ti(OiPr)4 system has been developed. The cis-glycidic amides were obtained in high yields and with moderate to excellent enantioselectivity (up to 99%).
- Liu, Gang,Zhang, Daming,Li, Jian,Xu, Guangyang,Sun, Jiangtao
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supporting information
p. 900 - 904
(2013/02/25)
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- Ru(II)-Pheox catalyzed N-H insertion reaction of diazoacetamides: Synthesis of N-substituted α-aminoamides
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An efficient protocol for the preparation of α-aminoamides was developed via the Ru(II)-dm-Pheox catalyzed N-H insertion reaction of various diazoacetamides with several amines, including aniline. This catalytic N-H insertion reaction was also applied to the synthesis of 2-(2-methylquinolin-4- ylamino)-N-phenylacetamide, a potential antileishmanial agent.
- Chanthamath, Soda,Thongjareun, Songkharm,Shibatomi, Kazutaka,Iwasa, Seiji
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supporting information; experimental part
p. 4862 - 4865
(2012/09/08)
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- PREPARATION OF DIAZO AND DIAZONIUM COMPOUNDS
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A method for making diazo-compounds, diazonium salts thereof and other protected forms of these compounds. Diaz-compounds are prepared by reaction of a tertiary phosphine reagent carrying a reactive carbonyl group with an azide. The reaction can also generate an acyl triazene which can be converted thermally or by addition of base to form the diazo-compound or the acyl triazene can be isolated. The method is particularly useful for conversion of azides carrying one or more electron withdrawing groups to diazo-compounds. The method can be carried out in aqueous medium under mild conditions and is particularly useful for conversion of azido sugars to diazo-compound and diazonium salts thereof under physiological conditions. Tertiary phosphine reagents, particularly those that are water-soluble, and precursors for preparation of the reagents are provided.
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Page/Page column 30
(2010/06/13)
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- Controlled diastereo-and enantioselection in a catalytic asymmetric aziridination
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Chiral polyborate based Bronsted acids prepared from the VANOL and VAPOL ligands are known to catalyze the reaction of diarylmethyl imines with diazoesters to give cis-aziridines. In the present work, this same catalyst is shown to catalyze the reaction of the same imines with diazoacetamides to give trans-aziridines with the same high asymmetric inductions as seen with cis-aziridines, enabling the development of an unprecedented universal catalytic asymmetric aziridination protocol. The substrate scope is broad and includes imines prepared from both electron-rich and electron-poor aromatic aldehydes and also from 1°, 2°, and 3° aliphatic aldehydes. The face selectivity of the addition to the imine was found to be independent of the diazo compounds. The (S)-VANOL or (S)-VAPOL derived catalyst will cause both diazoesters and diazoacetamides to add to the Si-face of the imine when cis-aziridines are formed and both to add to the Re-face of the imine when trans-aziridines are formed.
- Desai, Aman A.,Wulff, William D.
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supporting information; experimental part
p. 13100 - 13103
(2010/12/19)
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- Selective Reactions of Azide-Substituted α-Diazo Amides with Olefins and Alcohols Using Rhodium(II) Catalysts
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The synthesis and addition of azide-substituted α-diazo amides such as N-(4-azidophenyl)-α-diazoacetamide and N-(4-azido-2-hydroxyphenyl)-α-diazoacetamide to olefins and alcohols using either rhodium(II) acetate or preferably rhodium(II) pivalate provided cyclopropanecarboxamides and α-alkoxy amides, respectively, without disrupting the azide functionality.These azide-bearing α-diazo amides are potentially useful in the preparation of photoaffinity cross-linking reagents for studying the mechanism of action of natural products.
- Jeganathan, Alwarsamy,Richardson, Steward K.,Mani, Rajarathnam S.,Haley, Boyd E.,Watt, David S.
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p. 5362 - 5367
(2007/10/02)
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