Conjugate Additions of Nitroalkanes to Electron-Poor Alkenes: Recent Results
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(Nitroaldol) Reaction
MICROREVIEW DOI: 10.1002/ejoc.201101840 Biocatalytic Approaches to the Henry (Nitroaldol) Reaction Sinéad E. Milner,[a] Thomas S. Moody,[b] and Anita R. Maguire*[c] Keywords: Enzyme catalysis / Biocatalysis / C–C coupling / Nitroaldol reaction / Nitro alcohols Enantiopure β-nitro alcohols are key chiral building blocks approaches to the Henry (nitroaldol) reaction. The first for the synthesis of bioactive pharmaceutical ingredients. method is a direct enzyme-catalysed carbon–carbon bond The preparation of these target compounds in optically pure formation resulting in either an enantio-enriched or enantio- form has been the focus of much research and there has been pure β-nitro alcohol. The second approach describes the an emergence of biocatalytic protocols in the past decade. Henry reaction without stereocontrol followed by a biocata- For the first time, these biotransformations are the focus of lytic resolution to yield the enantiopure β-nitro alcohol. this review. Herein, we describe two principal biocatalytic Introduction The construction of carbon–carbon bonds is an essential element of synthetic organic chemistry. Among the various C–C bond forming reactions, the nitroaldol or Henry reac- tion[1] is one of the classical named reactions in organic synthesis. Essentially, this reaction describes the coupling of a nucleophilic nitro alkane with an electrophilic aldehyde or ketone to produce a synthetically useful β-nitro alcohol (Scheme 1).[2–5] Moreover, the Henry reaction facilitates the joining of two molecular fragments, under mild reaction conditions with the potential formation of two new ste- reogenic centres and a new C–C bond. The resulting β-nitro alcohols can undergo a variety of useful chemical transfor- mations which lead to synthetically useful structural motifs, e.g. -
Nitro Compounds As Oxidizing Agents
Class Book _______ Accession 1-f c6-- 111 Vol. ______ MORRISON . LIBRARY OF THE Municipal University of Wichita WICHITA. KANSAS THE IVERSI~Y ·o v !CHIT. NIT O COMPOUH ]).) 0 ID! ING AGENTw . SUBMITTED TO THE G.1. IDATE FACULTY IN C DI CY FOR THE ·n~G. OF TERO TS ) ) :l)-, .l)) )) ) ! ~ ):> ) ) ) .) ) .). J ) ,, ) ) ..) )) )) .) } ::> ) ) ) ) J ) J ) J ) .) ) .) ) .) ) . ) , ) ) ) ) ..) ) ) ) ) } ) J).) ' .J ) "):) ) ) .) .) ) ::> .) J ) ) ' J .) J ) ) s JUN t J.~32 Acknov~e gment is made to Professor ·orth A. Fletcher for his direction and assistance in the con uctance of this study. (ii) (ii) T BLE ·0] 1 COMTiilllT :e G.J.:J CKU ONLE DGlJCNT • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • . ii LIT OFT BLE • • • • • • • • • • • • • • • • • • • • • • • • , • • • , , • • • i V LI T OF FIGUl ~ ••••••••••••••••••••••• ' •••••••••• V IN Tl ODUCTI ON ••••••••••••••••••• , •••••••••••••••• l ~ pv. 11JI:E:t.i T L •· • • • • • • • • • • , • , •· • , , • • , • • • • • • • • • • • • • • • t ]? T B DFEECT OF TE1ft.PER TUHE •••• • • • • • • • • • • • .Id • C ffi.,' • y •••• •••••••••••• ............ •' • • • • • •••••• 13 LI 11: J:RE: CI TE'D. • • • • ••• , • • • • • • • • • • • • • • • , • • • • • •• 14 (iii) LI T O · BLE Table page I• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • .-:. • • • • • • 5 I I •• .. ................ ··~. ·~ ·· .....•..•........••.• 7 III. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 8 rv~.. J ••••••••••••••••••••••••••••••• .•••••••••••• -
Nitroso and Nitro Compounds 11/22/2014 Part 1
Hai Dao Baran Group Meeting Nitroso and Nitro Compounds 11/22/2014 Part 1. Introduction Nitro Compounds O D(Kcal/mol) d (Å) NO NO+ Ph NO Ph N cellular signaling 2 N O N O OH CH3−NO 40 1.48 molecule in mammals a nitro compound a nitronic acid nitric oxide b.p = 100 oC (8 mm) o CH3−NO2 57 1.47 nitrosonium m.p = 84 C ion (pKa = 2−6) CH3−NH2 79 1.47 IR: υ(N=O): 1621-1539 cm-1 CH3−I 56 Nitro group is an EWG (both −I and −M) Reaction Modes Nitro group is a "sink" of electron Nitroso vs. olefin: e Diels-Alder reaction: as dienophiles Nu O NO − NO Ene reaction 3 2 2 NO + N R h 2 O e Cope rearrangement υ O O Nu R2 N N N R1 N Nitroso vs. carbonyl R1 O O O O O N O O hυ Nucleophilic addition [O] N R2 R O O R3 Other reaction modes nitrite Radical addition high temp low temp nitrolium EWG [H] ion brown color less ion Redox reaction Photochemical reaction Nitroso Compounds (C-Nitroso Compounds) R2 R1 O R3 R1 Synthesis of C-Nitroso Compounds 2 O R1 R 2 N R3 3 R 3 N R N R N 3 + R2 2 R N O With NO sources: NaNO2/HCl, NOBF4, NOCl, NOSbF6, RONO... 1 R O R R1 O Substitution trans-dimer monomer: blue color cis-dimer colorless colorless R R NOBF OH 4 - R = OH, OMe, Me, NR2, NHR N R2 R3 = H or NaNO /HCl - para-selectivity ΔG = 10 Kcal mol-1 Me 2 Me R1 NO oxime R rate determining step Blue color: n π∗ absorption band 630-790 nm IR: υ(N=O): 1621-1539 cm-1, dimer υ(N−O): 1300 (cis), 1200 (trans) cm-1 + 1 Me H NMR (α-C-H) δ = 4 ppm: nitroso is an EWG ON H 3 Kochi et al. -
Part I: Nitroalkenes in the Synthesis of Heterocyclic Compounds† Cite This: RSC Adv.,2014,4, 48022 Azim Ziyaei Halimehjani,*A Irishi N
RSC Advances REVIEW View Article Online View Journal | View Issue Part I: Nitroalkenes in the synthesis of heterocyclic compounds† Cite this: RSC Adv.,2014,4, 48022 Azim Ziyaei Halimehjani,*a Irishi N. N. Namboothiri*b and Seyyed Emad Hooshmanda The applications of nitroalkenes in the synthesis of three- to five-membered O, N and S-heterocycles, including natural products are investigated in this review. These heterocyclic compounds were synthesized from nitroalkenes with a variety of substituents at the a and b-positions and those that were part of common and medium rings via a wide variety of reactions such as Michael addition reactions, epoxidation, [3 + 2] cycloaddition and many cascade/domino/tandem reactions. In addition, the potential of nitroalkenes to take part in multi-component and cascade reactions, particularly, in diastereo- and enantioselective versions is reviewed. The high reactivity of nitroalkenes and their Received 18th August 2014 potential to coordinate with the metal catalysts as well as organocatalysts signify them as efficient Accepted 16th September 2014 precursors in synthetic organic chemistry. Also, the flexibility of the nitro group in functional group DOI: 10.1039/c4ra08828j manipulations has expanded the scope of the nitro group, in general, and nitroalkenes, in particular, in www.rsc.org/advances organic synthesis. aFaculty of Chemistry, Kharazmi University, 49 Mofateh St., Tehran, Iran. E-mail: † Dedicated to Professor Mohammad Reza Saidi on the occasion of his 70th [email protected]; Fax: +98 (21) 88820992; Tel: +98 (21) 88848949 birthday. bDepartment of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India. E-mail: [email protected] Published on 17 September 2014. -
Electrochemistry and Photoredox Catalysis: a Comparative Evaluation in Organic Synthesis
molecules Review Electrochemistry and Photoredox Catalysis: A Comparative Evaluation in Organic Synthesis Rik H. Verschueren and Wim M. De Borggraeve * Department of Chemistry, Molecular Design and Synthesis, KU Leuven, Celestijnenlaan 200F, box 2404, 3001 Leuven, Belgium; [email protected] * Correspondence: [email protected]; Tel.: +32-16-32-7693 Received: 30 March 2019; Accepted: 23 May 2019; Published: 5 June 2019 Abstract: This review provides an overview of synthetic transformations that have been performed by both electro- and photoredox catalysis. Both toolboxes are evaluated and compared in their ability to enable said transformations. Analogies and distinctions are formulated to obtain a better understanding in both research areas. This knowledge can be used to conceptualize new methodological strategies for either of both approaches starting from the other. It was attempted to extract key components that can be used as guidelines to refine, complement and innovate these two disciplines of organic synthesis. Keywords: electrosynthesis; electrocatalysis; photocatalysis; photochemistry; electron transfer; redox catalysis; radical chemistry; organic synthesis; green chemistry 1. Introduction Both electrochemistry as well as photoredox catalysis have gone through a recent renaissance, bringing forth a whole range of both improved and new transformations previously thought impossible. In their growth, inspiration was found in older established radical chemistry, as well as from cross-pollination between the two toolboxes. In scientific discussion, photoredox catalysis and electrochemistry are often mentioned alongside each other. Nonetheless, no review has attempted a comparative evaluation of both fields in organic synthesis. Both research areas use electrons as reagents to generate open-shell radical intermediates. Because of the similar modes of action, many transformations have been translated from electrochemical to photoredox methodology and vice versa. -
John Ulric N E F
NATIONAL ACADEMY OF SCIENCES JOHN ULRIC N EF 1862—1915 A Biographical Memoir by M E L V I L L E L . W O L F R O M Any opinions expressed in this memoir are those of the author(s) and do not necessarily reflect the views of the National Academy of Sciences. Biographical Memoir COPYRIGHT 1960 NATIONAL ACADEMY OF SCIENCES WASHINGTON D.C. JOHN ULRIC NEF' June 14,1862-August 13,1915 BY MELVILLE L. WOLFROM OHN ULRIC NEF was a great pioneer in American chemistry. It was J he, along with Arthur Michael and Ira Remsen, who was mainly responsible for the transfer to the universities of the United States of the tenets of the actively growing science of organic chemistry from the laboratories of the great European universities of the time. Nef was a pioneer in theoretical organic chemistry, a great experimental- ist, and an inspiring trainer of men. His advanced students, the Ph.D. trainees, went into positions in the American universities, and espe- cially in the Middle West, determined to carry on the tradition of research. In the words of one: "We were determined to keep some research going if it were only to boil water." This establishment of chemical research in the American universities was carried out under the most difficult of conditions and with little support or understand- ing on the part of the administrators of these growing institutions, who mainly considered the science departments, in the liberal arts colleges, as units which cost a lot of money and produced results of doubtful cultural value. -
Total Synthesis of 1,2- Diamine Contained Alkaloids, Schizozygine, Vallesamidine and Strempeliopine (Chapter 1 and 2)
Towards Schizozygine Type Alkaloids: Total Synthesis of (+)-Vallesamidine and (+)-Strempeliopine by Xiangyu Zhang A thesis submitted in partial fulfilment of the requirement for the degree of Doctor of Philosophy Department of Chemistry University College London Declaration I, Xiangyu Zhang, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Signed: Date: i Abstract As a classic and powerful tool for carbon-carbon bond formation, the nitro-Mannich reaction has shown its versatility in drugs and natural products syntheses. The 1,2- diamine structure, a reduced moiety from nitro-Mannich adduct, is widely present in naturally occurring alkaloids and this feature suggested the potential application of nitro- mannich reaction in such alkaloids synthesis. This thesis showcases the nitro-Mannich reaction as a key strategic reaction through studies towards the total synthesis of 1,2- diamine contained alkaloids, schizozygine, vallesamidine and strempeliopine (Chapter 1 and 2). Initial studies on the schizozygine molecule (Chapter 3) generated a diastereoselective nitro-Mannich reaction on -branched nitroalkanes to synthesise complex -nitroamines with three contigurous chiral centres and syn,anti stereochemistry. This reaction was followed by a reductive cyclisation to achieve the functionalised piperidine ring C. Although the subsequent manipulation towards advanced shcizozygine intermediate was unsuccessful, the nitro-Mannich/reductive cyclisation sequence provided methodology for highly functionalised piperidine ring synthesis. A second generation route using nitro-Mannich reaction was accompanied by other nitro group chemistry, Michael addition, Tsuji-Trost allylation and nitro group reduction/C-N coupling reaction, to realise the quick and concise preparation of an A/B/C ring intermediate. -
Cu-Catalyzed Cross-Dehydrogenative Coupling: a Versatile Strategy for C–C Bond Formations Via the Oxidative Activation of Sp3 C–H Bonds
Cu-catalyzed cross-dehydrogenative coupling: A versatile strategy for C–C bond formations via the oxidative activation of sp3 C–H bonds Zhiping Li, D. Scott Bohle*, and Chao-Jun Li† Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6 Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved April 12, 2006 (received for review February 28, 2006) Cu-catalyzed cross-dehydrogenative coupling (CDC) methodolo- gies were developed based on the oxidative activation of sp3 C–H bonds adjacent to a nitrogen atom. Various sp, sp2, and sp3 C–H bonds of pronucleophiles were used in the Cu-catalyzed CDC reactions. Based on these results, the mechanisms of the CDC reactions also are discussed. C–H activation ͉ catalysis ͉ Baylis–Hillman reaction ͉ Mannich reaction ͉ Friedel–Crafts reaction –C bond formation reactions are among the most important Cprocesses in organic chemistry. Transition metal-catalyzed Scheme 1. Various cross-coupling methods for the formation of C–C bonds. cross-coupling reactions of various reactive functional groups are newer and more powerful methods for the formation of C–C bonds tromethane serving as both the reagent and solvent. Various copper [Scheme 1, Path A (1)]. However, these well developed cross- catalysts, such as CuCl, CuBr, CuI, Cu(OTf), CuCl , CuBr , coupling reactions must use prefunctionalized starting materials. 2 2 Cu(OTf) , and Cu(OAc) ⅐H O, were examined at room tempera- Therefore, in the formation of a single chemical bond, an extra 2 2 2 ture (RT), and the desired product was obtained in all cases. -
Nitroalkanes As Central Reagents in the Synthesis of Spiroketals
Molecules 2008, 13, 319-330 molecules ISSN 1420-3049 © 2008 by MDPI www.mdpi.org/molecules Review Nitroalkanes as Central Reagents in the Synthesis of Spiroketals Roberto Ballini 1,*, Marino Petrini 1 and Goffredo Rosini 2 1 Dipartimento di Scienze Chimiche, Università di Camerino, via S.Agostino, 1, I-62032 Camerino, Italy; E-mail: [email protected]. 2 Dipartimento di Chimica Organica ‘A. Mangini’, Alma Mater Studiorum–Università di Bologna, Viale del Risorgimento n. 4, 40136 Bologna, Italy; E-mail: [email protected]. * Author to whom correspondence should be addressed; E-mail: [email protected]; Fax: +39 0737 402297 Received: 8 January 2008; in revised form: 2 February 2008 / Accepted: 4 February 2008 / Published: 7 February 2008 Abstract: Nitroalkanes can be profitably employed as carbanionic precursors for the assembly of dihydroxy ketone frameworks, suitable for the preparation of spiroketals. The carbon-carbon bond formation is carried out exploiting nitroaldol and Michael reactions, while the nitro to carbonyl conversion (Nef reaction) ensures the correct introduction of the keto group. Several spiroketal systems endowed with considerable biological activity can be prepared using this synthetic strategy. Keywords: Conjugate addition, Nef reaction, nitroaldol reaction, nitroalkanes, spiroketals. 1. Introduction The spiroketal moiety is a key motif embodied in a large number of natural products present in plants, fungi, insect secretions, shellfish toxins and other living organisms [1-5]. Many of these compounds also display a considerable biological activity as antibiotics and pheromones. From a synthetic standpoint, among various practical strategies currently available for the assembling of the spiroketal unit, the one based on the acid promoted intramolecular acetalization of dihydroxy ketone derivatives 1 firmly occupies a prominent position (Scheme 1). -
UNITED STATES PATENT Orricsg. 2,623,904 Nrrao ALDEHYDES and Preraaarion TPEREGF Curtis W
Patented Dec. 30, ‘1952 2,623.04 UNITED STATES PATENT orricsg. 2,623,904 nrrao ALDEHYDES AND PRErAaArioN _ TPEREGF Curtis W. Smith, ‘Berke ley, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application December 3, 1948, Serial No. 63,455 13 Claims. (Cl. 260-601) substituent group is directly linked to an- all This invention relates to organic compounds phatic carbon atom to which there is also direct and to a process for the preparation of organic ly attached an atom of hydrogen, nitro-aldehydes compounds. rather than nitro-alcohols, are produced. ' More particularly, the invention relates to The alpha-methylidene aldehydes are those nitrmaldehydes and to a process for the prepara aldehydes which have directly linked to the car tion of nitro-aldehydes. The invention also re bon atom in the alpha position relative to the lates to a new and unexpected reaction of ‘un formyl group a methylidene radical (CI-I2=),. saturated aldehydes with organic nitro com Thus, they are the alpha, beta-ole?nic aldehydes pounds whereby the nitro-aldehydes of the in in which the remaining valences of thecarbon vention may be prepared. atom in the beta position are satis?ed byatoms It has been discovered that nitro-aldehydes of hydrogen. The alpha-methylidene aldehydes may be prepared by condensing alpha-methyli may also be described by means of the formula dene aldehydes with nitro-substituted compounds wherein a nitro substituent group is directly linked to an aliphatic carbon atom to which there is also directly attached an atom of hydrogen. -
Open Sacher - Phd Dissertation.Pdf
The Pennsylvania State University The Graduate School Eberly College of Science PROGRESS TOWARD A TOTAL SYNTHESIS OF THE LYCOPODIUM ALKALOID LYCOPLADINE H A Dissertation in Chemistry by Joshua R. Sacher © 2012 Joshua R. Sacher Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy May 2012 ii The dissertation of Joshua Sacher was reviewed and approved* by the following: Steven M. Weinreb Russell and Mildred Marker Professor of Natural Products Chemistry Dissertation Advisor Chair of Committee Raymond L. Funk Professor of Chemistry Gong Chen Assistant Professor of Chemistry Ryan J. Elias Frederik Sr. and Faith E. Rasmussen Career Development Professor of Food Science Barbara Garrison Shapiro Professor of Chemistry Head of the Department of Chemistry *Signatures are on file in the Graduate School iii ABSTRACT In work directed toward a total synthesis of the Lycopodium alkaloid lycopladine H (21), several strategies have been explored based on key tandem oxidative dearomatization/Diels-Alder reactions of o-quinone ketals. Both intra- and intermolecular approaches were examined, with the greatest success coming from dearomatization of bromophenol 84b followed by cycloaddition of the resulting dienone with nitroethylene to provide the bicyclo[2.2.2]octane core 203 of the natural product. The C-5 center was established via a stereoselective Henry reaction with formaldehyde to form 228, and the C-12 center was set through addition of vinyl cerium to the C-12 ketone to give 272. A novel intramolecular hydroaminomethylation of vinyl amine 272 was used to construct the 8-membered azocane ring in intermediate 322, resulting in establishment of 3 of the 4 rings present in the natural product 21 in 9 steps from known readily available compounds. -
First and Efficient Method for Reduction of Aliphatic and Aromatic Nitro Compounds with Zinc Borohydride As Pyridine Zinc Tetrah
Journal of the Chinese Chemical Society, 2003, 50, 267-271 267 First and Efficient Method for Reduction of Aliphatic and Aromatic Nitro Compounds with Zinc Borohydride as Pyridine Zinc Tetrahydroborato Complex: A New Stable Ligand-Metal Borohydride Behzad Zeynizadeh* and Karam Zahmatkesh Chemistry Department, Faculty of Sciences, Urmia University, Urmia 57159, Iran Pyridine zinc tetrahydroborate, [(Py)Zn(BH4)2], as a new stable ligand-metal borohydride, is prepared quantitatively by complexation of 1:1 zinc borohydride and pyridine at room temperature. This reagent effi- ciently reduces different aromatic and aliphatic nitro compounds to their primary amines in refluxing THF. In addition, the reduction shows chemoselectivity for aliphatic nitro compounds over the aromatic nitro com- pounds. Keywords: Reduction; Zinc borohydride; Nitro compound; Chemoselectivity; Amine. INTRODUCTION been reviewed. These successes prompted us to prepare 13 [(Py)Zn(BH4)2] and investigate its reducing ability. In our For over forty years, sodium borohydride has been study, we also observed that this reagent efficiently reduces widely recognized as the reagent of choice for the reduction aliphatic and aromatic nitro compounds to their correspond- of carbonyl compounds and acid chlorides in protic solvents.1 ing primary amines in refluxing THF (Scheme I). Over the past decades, the utility of sodium borohydride has been greatly expanded and different techniques and modifi- Scheme I cations have been developed for it to reduce organofunctional groups in various