Similar results can sometimes also be achieved with nanoparticles. To access a cheminform abstract of an article which was published elsewhere, please select a full text option. Regioselective nucleophilic additions to tricarbonyl. Regioselective addition of tbutyllithium to tricarbonyl. Preparation of arene chromium tricarbonyl complexes using continuousflow processing. Stereoselective reactions of arene chromium tricarbonyl complexes. It was envisaged that the addition of an organometallic reagent to the carbonyl group within orthosubstituted aryl aldehydechromium tricarbonyl complex 4 may be a selective alternative procedure to create a benzylic stereogenic centre, and that reduction of the corresponding orthosubstituted aryl ketonechromium tricarbonyl complexes 7 r.
Arene tricarbonyl complexes of chromium 0, molybdenum. This yellow crystalline solid compound is soluble in common. Treatment of the chiral complex 1 with smi 2 gives tricycle 2 selectively by a 5. Romp and rcm zieglernatta catalyst zieglernatta catalysts are used to polymerize. Download ris reference manager download bib bibtex back to article. A continuousflow approach to the direct synthesis of arene chromium tricarbonyl complexes is presented. The structures of nine crystalline complexes were determined by xray. Download a prospectus postgraduate research admissions postgraduate research fees for postgraduate research.
The complexation of an arene to a chromium tricarbonyl unit changes its chemical behavior, giving rise. The 1,3dipolar cycloaddition products of c,ndisubstituted nitrones and different in situ prepared mononsubstituted nitrones to. Influence of substituents in tricarbonyl arene chromium. Arene tricarbonyl complexes of chromium o, molybdenumo, md tungsteno by darrell keith wells a dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of doctor of philosophy major subject. Abstract orthobutenylchlorobenzene tricarbonylchromium complexes undergo intramolecular pd catalyzed cyclizations heckreactions without decomplexation andor alkene isomerization. Preparation of arene chromium tricarbonyl complexes using. A thesis submitted in partial fulfillment of the requirements for the degree of master of science in chemistry. All tricarbonylchromium complexes were fully characterized.
Citeseerx document details isaac councill, lee giles, pradeep teregowda. Both styrene and ethynylbenzene complexes react with alkynes and olefins. The fourth chapter is a study of arene chromium tricarbonyl complexes of dibenzyl ethcl and a dibclizy laminc, dnd their as mmetr ie dept otonatioll. Aryl aldehyde and aryl ketone chromium tricarbonyl complexes orthosubstituted with the chiral auxiliary omethyln. Initial nucleophilic addition of organolithium reagents to a carbonyl moiety is followed by a 1,4carbon to oxygen silyl migration brook rearrangement and alkylation of the resultant aryl anion. In 1957, fischer and ofele published the preparation of tricarbonyl. Benzene chromium 0 tricarbonyl is one of numerous organometallic compounds also known as metalorganic, organoinorganic and metalloorganic compounds sold by american elements under the trade name ae organometallics for uses requiring nonaqueous solubility such as recent solar energy and water treatment applications. Asymmetric synthesis of secondary benzylic alcohols via arene. Benzene chromium0 tricarbonyl is one of numerous organometallic compounds also known as metalorganic, organoinorganic and metalloorganic compounds sold by american elements under the trade name ae organometallics for uses requiring nonaqueous solubility such as recent solar energy and water treatment applications. Asymmetric synthesis of secondary benzylic alcohols via arene chromium tricarbonyl complexes aryl aldehyde and aryl ketone chromium tricarbonyl complexes orthosubstituted with the chiral auxiliary omethyln.
Initial nucleophilic addition of organolithium reagents to a carbonyl moiety is followed by a 1,4carbon to oxygen silyl migration brook rearrangement and alkylation of. Reactions that focus on nucleophilic additions to the chromium. Tricarbonyl arene chromium complexes are susceptible to oxidation in solution and should be handled in an. Tricarbonyl arene chromium complexes are susceptible to oxidation in solution and should be handled in an inert atmosphere. Intramolecular pd catalyzed carbocyclization reactions with planar chiral arene tricarbonyl chromium complexes. Arene tricarbonyl complexes of chromium 0, molybdenum 0. The aqueous layers from the chromium mediated reactions and any other waste materials should be disposed of properly. Benzene chromium tricarbonyl is an organometallic compound with the formula crc 6 h 6co 3. In each case, the nucleophiles would then be expected to approach complexes 5 and 8 anti to the bulky chromium tricarbonyl moiety, giving rise to the epimeric adducts 6 and 9, respectively. The first rr arene chromium tricarbonyl compound was synthesized by fischer and ofele in 1957.
By working in flow mode, it is possible to avoid some of the problems of batch synthesis, especially sublimation of the crco6 starting material and the competitive decomposition of the product during the lengthy reaction times. Intramolecular pd catalyzed carbocyclization reactions. Benzylic activation and stereochemical control in reactions. The original article is trackable via the references option. The cr atom is bound to the pyridine ring via the 7relectron system and is situated directly below the heteroarene ring centre. Chromium arene complexes in organic synthesis semantic scholar. Stereoselective bisfunctionalizations of arene chromium. Photolysis of arene chromium tricarbonyl complexes in. Mathews department of chemistry, clemson university, clemson, so, 29634 usa abstract. The intramolecular ring closure of the obtained crco3 complexed. Chromium arene complexes in organic synthesis marta rosillo, gema domnguez and javier pe. However, the following two methods are the most commonly employed ones.
Wells, darrell keith, arene tricarbonyl complexes of chromium 0, molybdenum 0, and tungsten 0 1969. Pdf download buy article permissions and reprints all articles of this category arene chromium tricarbonyl complexes have been widely used in synthetic organic chemistry. This yellow crystalline solid compound is soluble in common nonpolar organic solvents. Scission and regeneration of carboncarbon bonds some important classes of olefin metathesis reactions are. Intramolecular pd catalyzed carbocyclization reactions with. In the latter case the ketyl radical adds directly to the complexed arene. The structures of nine crystalline complexes were determined by xray diffraction. Benzenechromium tricarbonyl is an organometallic compound with the formula crc 6 h 6co 3. Molecules free fulltext tricarbonylh6arenechromium0. The synthesis of enynes connected through chromium complexed aromatic rings is developed. Photolysis of arene chromium tricarbonyl complexes. Arene chromium tricarbonyl chemistry, cheminform on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
These compounds may be easily decomplexed and deprotected to give the. The second chapter looks at the synthesis of a novel benzyl phosphine chromium tricarbonyl complex and attempts to asymmetrically deprotonate the molecule in. Heckreaction planar chirality arene complex chromium. Asymmetric synthesis of secondary benzylic alcohols via. The latter part deals with the chemistry of arene chromium tricarbonyl complexes and how these molecules have been used in asymmetric synthesis and as ligands in asymmetric catalysis. As a result, these reactions of chromium arene complexes are often faster than analogous reactions of free arenes. The two intermediates selected were piacetophenone chromium tricarbonyl and pibenzyl bromide chromium. Compounds of chromium are toxic and must be used in a wellventilated fume hood.
The optically pure tricarbonyl h62substituted benzaldehydes chromium are used as chiral auxiliaries in the condensation with a series of doubly lithiated carboxylic acids. Proposed strategy to create benzylic stereogenic centres. A thesis submitted in partial fulfillment of the requirements. The complexation of a crco unit to an aromatic hydrocarbon enhances the benzylic position towerds attack by base and the resulting carbanion reacts with carbonyl compounds to produce a complexed alcohol. Sorry, we are unable to provide the full text but you may find it at the following locations. Molecules free fulltext tricarbonylh6arenechromium. Benzylic activation and stereocontrol in tricarbonyl. Benzylic functionalization of arenetricarbonylchromium. Chromium arene complexes in organic synthesis marta rosillo, gema dom. The molecular structure of tricarbonyl rl6pyridine chromium 0, crco3c5h5n, is presented here. Chromium arene complexes in organic synthesis chemical society.
The molecule adopts a geometry known as piano stool because of the planar arrangement of the aryl group and the presence of three co ligands as legs on the. Arene exchange reactions of arenetricarbonylchromium complexes. The unusual features include a large upfield shift of alkene proton chemical shifts on complex formation, but within the metals the order. Thiation of arene tricarbonyl chromium 0 complexes. The intramolecular ring closure of the obtained crco3 complexed bhydroxyacids affords the optically pure blactones in satisfactory yield. Grubbs catalyst a catalyst for olefin metathesis reactions olefin metathesis reaction. Contact us postgraduate research postgraduate certificates and diplomas. Journal of the chemical society, perkin transactions 1 regioselective nucleophilic additions to tricarbonyl. Secondly, we are interested in the 2methylanisole chromium tricarbonyl complex, which has an electron withdrawing oxygen attached to the arene ring which should pull electron density from the metal, leaving less to backbond with the carbonyl ligands, resulting in a. Read photolysis of arene chromium tricarbonyl complexes in presence of amineboranes. By working in flow mode, it is possible to avoid some of the problems of batch synthesis, especially sublimation of the crco 6 starting material and the competitive decomposition of the product during the lengthy reaction times. Tricarbonylcycloheptatrienechromium0 98% sigmaaldrich.
Khand reaction occurs in a totally diastereoselective manner. Hexacarbonylchromium is widely used as a catalyst for isomerization of alkenes. Tricarbonylcycloheptatriene chromium0 98% cas number 12125723. The synthesis of enynes connected through chromiumcomplexed aromatic rings is developed.
The complexation of an arene to a chromium tricarbonyl unit changes its. Tricarbonyl mesitylene chromium 0 98% cas number 12129678. Phil new college trinity 1989 oxford abstract this thesis describes the application of arene crco3 methodology to the stereoselective and enantioselective synthesis of substituted arenes. Benzylic activation and stereocontrol in tricarbonylarene. Benzenechromium tricarbonyl is an organometallic compound with the formula crc6h6co3. Synthesis and selected reactions of piarene chromium. The genet thon of new c2symmetric ethers with high enantioselectivity is demonstrated. In these reactions the influence of electrondonating and electronaccepting substituents in the tricarbonyl arene chromium system is weak. Nuclear magnetic resonance study of arene metal tricarbonyl.
Novel arene chromium carbonyl complexed mustard agents have been prepared. Subsequent experimentation revealed that, in most cases, rrchromiu. An efficient method has been developed for the stereoselective bisfunctionalization of arene chromium tricarbonyl complexes. Epimeric pyrroloimidazolone auxiliaries in the diastereoselective synthesis of chiral nferrocenylnphenyl ligands and arene chromium tricarbonyl complexes by cody wilsonkonderka, b.
The molecule adopts a geometry known as piano stool because of the planar arrangement of the aryl group and the presence of three co ligands as legs on the chromium bond axis. Jun 15, 2011 read photolysis of arene chromium tricarbonyl complexes in presence of amineboranes. Brought to you by the organic reactions wiki, the online collection of organic reactions. Cheminform is a weekly abstracting service, delivering concise information at a glance that was extracted from about 100 leading journals. It is involved in the hydrogenation of 1,3conjugated dienes and oxidation of allylic and benzylic positions. These intermediates would be particularly wellsuited for the preparation of monocomplexed diaryl compounds. In this article, catalytic activities of these complexes in hydrogenation and isomerization are discussed. The two intermediates selected were piacetophenone chromium tricarbonyl and pibenzyl bromide chromium tricarbonyl. Tricarbonylmesitylene chromium0 98% cas number 12129678. Nonracemic derivatives of a tricarbonyl eta6 arene chromium complex derived from 1,3dihydroisobenzofuran are also prepared in up to 99% ee by chiral base deprotonation, and trends in the. Download ris reference manager download bib bibtex cited references.
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