Gm58160 the development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a longstanding goal of chemical research. Regioselective synthesis of this kind of indoles is dicult by fischer method. However, the mechanism of the protonation of the titanacycle by. Read hydroamination of alkynes catalyzed by palladiumbenzoic acid. The catalytic hydroamination of alkynes, cheminform 10. Enamines are versatile intermediates in organic synthesis, and although catalytic methods have been developed for their synthesis by alkyne hydroamination. Thus, to t he best of our knowledge, hydro imination of terminal alkynes is still unknown to date. Chapter 3 base catalyzed hydroamination of terminal alkynes 86 3. Conspectusinter or intramolecular hydroamination reactions are a paradigmatic example of modern sustainable organic chemistry, as they are a catalytic, 100% atomeconomical, and wastefree process of fundamental simplicity in which an amine is added to an alkyne substrate. Intermolecular copetype hydroamination of alkynes using hydrazines. Frauke pohlki and sven doye institut fur organische chemie, universitat hannover, schneiderberg 1b. The major product is predicted by the markovnikov rule, which states that when a hydrogen halide is added to an asymmetrically substituted alkene, the major product results from the addition of the hydrogen atom to the double. In the ideal case, hydroamination is atom economical and green.
The research progress in metals catalyzed hydroamination of alkenes and alkynes from the perspective of reaction mechanism is categorized. And this isnt considered to be the perfect mechanism for alkynes, but were going to start with that, just to show why this is markovnikovs, in terms of regiochemistry. Hydroamination is a reaction that involves the addition of a hydrogen and an amino group across an unsaturated cc bond, such as that in alkenes or in alkynes. Metalation of terminal alkynes is a significant side reaction that occurs under these conditions.
Hence,inanumberof casesthealkynewillbethecostdeterminingfactor. Catalytic additions of ammonia or primary and secondary amines to nonactivated alkenes and alkynes are called hydroaminations. Reactions that employ alkynes as starting materials are synthetically versatile, since alkynes can be prepared by a variety of strategies, including sonogashira coupling, nucleophilic addition of metal acetylides 14, and homologation of carbonyl. Gold i catalyzed enantioselective intramolecular hydroamination of allenes rebecca l. Compared to intramolecular cyclizations, intermolecular hydroamination of alkynes is scheme3.
Cn bonds are ubiquitous in organic molecules and their formation is crucial in organic synthesis. Hydration and hydroamination of 1alkynes with ruthenium. The hydroamination is sometimes accompanied by undesired side reactions like cyclotrimerization of alkyne component. In contrast to the hydroamination of alkenes, which gives access to stable amines directly, the hydroamination of alkynes. Under different sets of conditions, both enamines and alkylamines could be selectively prepared from the same starting materials. N bonds through the addition of amines to unsaturated c. A rutheniumcatalyzed intermolecular, antimarkovnikov hydroamination of vinylarenes with secondary aliphatic and benzylic amines is reported. Coppercatalyzed hydroamination of alkenes and alkynes reported by alfredo garcia september 29th, 2015 introduction amines are found in a variety of biologically active natural products and medicines. Therefore, it is a facile and highly atomeconomical way to access industrially relevant nitrogen containing basic and fine. Basemediated hydroamination of symmetrical internal alkynes 26 in a recent study, zirconiumcatalyzed hydroamination of both internal and terminal alkynes with sterically demanding and less demanding primary amines was achieved successfully in moderate to good yields but the reaction failed with. Catalyzed hydroamination of siloxy alkynes, angewandte chemie international edition on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Pdf intermolecular copetype hydroamination of alkynes. Hydroamination of alkynes catalyzed by palladiumbenzoic. The mechanism of hydroamination of allenes, alkynes, and.
Pdf new feats of alkene and alkyne asymmetric hydroamination. Hydroamination of 1alkynes to ketimines the addition of amines to alkynes to give imines is a fundamental reaction but only few successful examples of intramolecular reaction are known. The success in this area of research was made possible through the large body of precedent in copperi hydride catalysis and. Pdf herein, we report the synthesis, characterization, and catalytic performance. Reactions that employ alkynes as starting materials are synthetically versatile, since alkynes can be prepared by a variety of strategies, including sonogashira coupling, nucleophilic addition of metal acetylides 14, and. And it closely parallels the hydrohalogenation of alkenes. The addition of hydrogen halides to asymmetrically substituted alkenes leads to two products. The application of the titaniumcatalyzed hydroamination of alkynes toward the synthesis of benzylisoquinoline derivatives. The halide will add to the more substituted carbon following markovnikovs rule. Cuhcatalyzed hydroamination has also been successfully applied to alkynes, a readily accessible class of substrates. So lets take a look at one of the proposed mechanisms for the hydrohalogenation of alkynes. Coppercatalysed selective hydroamination reactions of alkynes. For that reason, the hydroamination procedures for alkynes developed so far might be the basis for future hydroamination processes for alkenes. Hung wai cheung, chau ming so, kwok hung pun, zhongyuan zhou and chak po lau, cheminform abstract.
Hydrocyanation of alkenes and alkynes refers to the transitionmetalmediated or catalyzed addition of hydrogen cyanide across a carboncarbon. Control reactions conducted without ligand or acid did not form the amine. Titanaazacyclobutenes and titanaazacyclobutanes are proposed as intermediates in the catalytic cycle,2a, 4, 5 in analogy to the cp 2 zrnhr 2catalyzed hydroamination of alkynes or the stoichiometric reaction of allenes with zirconium and titanium pyridine imido derivatives. Hydroamination of alkenes and alkynes overall reaction is thermodynamically favorable with negative reaction entropy, which means high temperature is not able to overcome high activation barrier. Hydration and hydroamination of 1alkynes with, hive.
Chapter 3 basemediated hydroamination of terminal alkynes. Pdf hydroamination of aromatic alkynes to imines catalyzed by. Hydrogenbondpromoted metalfree hydroamination of alkynes. Twostep reaction in which an alkene is converted to an alkene with a hydroxyl substituent which may tauromerize to a carbonyl. Mar 12, 2020 the cover feature shows a procedure that enables the reductive hydro. Hydrosilylation, also known as hydrosilation, is one of the most useful catalytic reactions leading to the formation of organsilanes and organosilicones, which have a variety of applications in industry and as intermediates in organic chemistry. Hydroamination of 1 alkynes to ketimines the addition of amines to alkynes to give imines is a fundamental reaction but only few successful examples of intramolecular reaction are known. Dean toste department of chemistry, university of california, berkeley, california 94720 received december 9, 2006. The product is a haloalkane also called an alkyl halide. While the hydroamination of terminal alkenes and alkynes under metal catalysis has been widely developed, the corresponding reactions with. The mechanism of the hydroboration of alkynes is similar to that of alkene hydroboration. These reactions of fundamental simplicity represent the most atom efficient processes for the formation of amines, enamines and imines, which are important bulk and fine chemicals o. However, the mechanism of the protonation of the titanacycle by the amine is not. Hydroamination of aromatic alkynes to imines catalyzed by.
Jan 04, 2007 read the catalytic hydroamination of alkynes, cheminform on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Rutheniumcatalyzed antimarkovnikov hydroamination of. Hydrocyanation of alkenes and alkynes organic reactions. We became interested in developing hydroamination reactions of alkynes as a convenient and powerful means of accessing aminated products fig. Catalytic hydroaminations of alkenes, allenes, and dienes which may be inter or intramolecular afford amines, imines, and enamines eq. Copper hydride catalyzed hydroamination of alkenes and alkynes. Hydroamination of aromatic alkynes to imines catalyzed by pd. Cheminform is a weekly abstracting service, delivering concise information at a glance that was extracted from about 200 leading journals. Direct addition of amines to alkenes and alkynes thomas e. Nov 16, 2019 hydroamination is the addition of an nh bond of an amine across a carboncarbon multiple bond of an alkene, alkyne, diene, or allene. Palladiumcatalyzed intramolecular asymmetric hydroamination, hydroalkoxylation, and hydrocarbonation of alkynes. Jan 04, 2016 cuhcatalyzed hydroamination has also been successfully applied to alkynes, a readily accessible class of substrates.
Metalfree hydroamination of alkynes thieme chemistry. Among those protocols, the hydroamination reaction constitutes an atome. Markovnikov addition of secondary amines to aromatic 1. Copper hydridecatalyzed hydroamination of alkenes and alkynes. Recent advances in the hydrosilylation of alkynes emily a.
Heres the hydroborationoxidation of alkyne reaction. The catalytic hydroamination of alkynes chemical society. Hydroborationoxidation of alkynes video khan academy. Among others, epoxideopening arene annulations, intramolecular coupling of carbonyl groups intermolecular hydroamination. The preparations of alkynes are very similar to those of the alkenes. The catalytic hydroamination of a alkenes, b alkynes, c allenes, and d dienes leads to amines, imines, and enamines. Applying our catalytic hydroamination system to the reaction of anilines and 1subsituted2propyne1ols scheme 6 at slightly higher temperature 140. The cover feature shows a procedure that enables the reductive hydro. Hydroamination is the addition of an nh bond of an amine across a carboncarbon multiple bond of an alkene, alkyne, diene, or allene. Computational insight into a goldi nheterocyclic carbene.
Hydroamination is the addition of an nh bond of an amine across a carbon carbon multiple bond of an alkene, alkyne, diene, or allene. Selective hydroamination of terminal alkynes with primary aryl amines is catalyzed by an unprecedented welldefined silicasupported tantalum complex. This reaction may be used to synthesize nitriles from alkenes or alkynes in a markovnikov or antimarkovnikov fashion. Compared to intramolecular cyclizations, intermolecular hydroamination of alkynes is. Amines are common in finechemical, pharmaceutical, and agricultural industries.
Chapter 3 base catalyzed hydroamination of terminal alkynes 91 the effective addition of heterocyclic amines followed the antimarkovnikovs rule. Then, a description on the use of heterogeneous catalysts, base and acid catalyzed hydroamination, and some stoichiometric reactions. Development of catalysts for the hydroamination of olefins pdf. The addition of bh 3 from b 2 h 6 to an alkyne is a stereospecific cis addition and the boron atom is regiospecifically added to. The reagents and the ru catalyst are assembled within nanomicelles that release the final product into the water.
Lomonosov moscow state university, 119991 moscow, russian federation. Simple and efficient auibased catalyst for hydroamination. Therefore, it is indispensable to identify alternative catalytic procedures for the discussed hydroamination reactions. Mechanistic study of hydroamination of alkyne through. The highest yield 98% was achieved with the simplest aniline 3c simple and efficient au i based catalyst for hydroamination of alkynes maksim v.
The combination of rucod2methylallyl2, 1,5bisdiphenylphosphinopentane, and triflic acid was the most effective catalyst of those tested. Initial experiments to convert alkynes into primary amines using benzylamine as an ammonia equivalent in the hydroamination step followed by hydrogenation of the resulting imine have met with only limited success because benzyl. Applications of different titanium based reagents in various organic reactions leading to the formation of heterocyclic compounds are discussed. This includes the mechanistic aspects of hydroamination regarding its early and late transition. The main preparative reactions involve the elimination of groups or ions from molecules, resulting in the formation of. Antimarkovnikov hydroimination of terminal alkynes in. Coppercatalyzed selective hydroamination reactions of alkynes.
Hydroamination reactions of alkenes organic reactions wiki. However, the mechanism of the protonation of the titanacycle by the amine is not well understood. Hydroamination, the addition of hnr 2 across a carboncarbon. Chapter 2a basemediated hydroamination of symmetrical. These reactions include the addition of amines, alcohols, carboxylic acids, thiols, 1,3dicarbonyls, alkenes, alkynes and arenes to either alkenes, alkynes or allenes. The application of the titaniumcatalyzed hydroamination.
The hydrohalogenation of alkenes involves breaking a carbon to carbon double bond, followed by the electrophilic addition of a hydrogen atom and halogen. Ironcatalysed hydrofunctionalisation of alkenes and alkynes. The loss of a hydrogen atom and a halogen atom from adjacent alkane carbon atoms leads to the formation of an alkene. Among the plethora of cn bondforming reactions available in the arsenal of organic chemists, the hydroamination of alkynes is a very useful process, which is generally performed under metal catalysis. This includes the mechanistic aspects of hydroamination regarding its early and late transition metal catalysts. Analogous to hydroboration reactions with r 2 bh, hydroalumination with r 2 alh leads to the attachment of aluminium at the carbon less able to stabilize developing positive charge antimarkovnikov selectivity.
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