Reactions at the coordinated trichloromethyl isocyanide. Part VII. α-Chloroalkenylisocyanide versus oxazolin-2-ylidene(ato) complex formation

Langenhahn, Volker; Beck, G.; Zinner, G.; Lentz, Dieter; Herrschaft, Bernhard; Fehlhammer, Wolf Peter

doi:10.1016/j.jorganchem.2007.03.005

Cited by 7 publications

(13 citation statements)

References 31 publications

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“…9 A rare case of cyclization of ketones with coordinated isocyanide has been described. 10 Thiazol-2-ylidene carbene complexes are frequently prepared by reaction of lithiated thiazoles with the appropriate metallic fragment and subsequent alkylation or protonation of the corresponding thiazolyl derivative. 11 Methods implying in situ deprotonation of thiazolium salts have also been used.…”

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confidence: 99%

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Ruiz

Perandones

2009

Chem. Commun.

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Oxazole and thiazole molecules N-coordinated to manganese(I) are transformed into their corresponding 2,3-dihydrooxazol-2-ylidene and 2,3-dihydrothiazol-2-ylidene carbene tautomers by acid-base reactions, and subsequently transmetalated to gold(I), via isolable heterometallic intermediates.Oxazole (1a) and thiazole (1b) are simple molecules of great relevance in heterocyclic chemistry and important structural elements in many natural products. 1 Their corresponding carbene tautomers, 2,3-dihydrooxazol-2-ylidene (2a) and 2,3-dihydrothiazol-2-ylidene (2b), derived from a 1,2-hydrogen shift (Scheme 1) are not stable, and this has been rationalized on the base of theoretical calculations, 2 deuterium exchange NMR measurements 3 and argon matrix experiments. 4 On the other hand, whereas a large number of NHC complexes of imidazol-2-ylidene type are known, 5 many of them successfully applied in homogeneous catalysis, 6 relatively few examples of coordination complexes containing carbene ligands of oxazol-2-ylidene or thiazol-2-ylidene types have been described. Methods for preparing oxazol-2-ylidene carbene complexes are limited to intramolecular cyclization of functionalized hydroxy isocyanides 7 or reaction of epoxides with hydrogen isocyanide complexes, 8 the classical route involving in situ deprotonation of oxazolium salts being very infrequently encountered in the literature. 9 A rare case of cyclization of ketones with coordinated isocyanide has been described. 10 Thiazol-2-ylidene carbene complexes are frequently prepared by reaction of lithiated thiazoles with the appropriate metallic fragment and subsequent alkylation or protonation of the corresponding thiazolyl derivative. 11 Methods implying in situ deprotonation of thiazolium salts have also been used. 12 Whereas complexes containing carbene 2b are known, 11b to the best of our knowledge, so far there has been no report of a complex containing the oxazolin-2-ylidene carbene 2a itself. We have recently reported that coordinated imidazoles can be transformed into their corresponding NHC complexes by means of acid-base treatments. 13 We have now found that this methodology can be applied to oxazole (1a) and thiazole (1b) molecules coordinated to manganese(I), which can easily be converted to oxazolin-2-ylidene (2a) and thiazolin-2-ylidene (2b) ligands, respectively. Preliminary results on the use of these complexes as carbene transfer agents are also shown herein.Azoles 1a,b easily coordinate to Mn(I) when reacting with the precursor complex fac-[Mn(OClO 3 )(CO) 3 (bipy)] (3) to afford the cationic complexes 4a,b (Scheme 2). As can be seen in the X-ray diffraction study carried out on 4b (Fig. 1),z the azole ligands in these complexes are N-coordinated. 4a,b are readily deprotonated at the C2 carbon atom of the azole heterocycle when treated with K t OBu to afford neutral derivatives 5a,b containing oxazolyl and thiazolyl ligands. Subsequent protonation at the nitrogen atom gives the carbene complexes 6a,b in quantitative yields, completing the metal and ac...

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confidence: 99%

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Ruiz

Perandones

2009

Chem. Commun.

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“…The main driving force for the cyclization to 9 probably is the ring aromatization, which requires the C 3 –H bond to be cleaved, a process not feasible for 2a . Here, the primary addition product with MeO 2 C–C≡C–CO 2 Me stabilizes by rearrangement into the well‐known α‐chloroalkenyl isocyanide structural unit 1 (cf. Section 3) and a new phosphorus ylide, which is much less reactive because of extensive conjugation.…”

Section: Resultsmentioning

confidence: 99%

“…Depending on the stoichiometry and the reaction conditions – such as the presence of traces of water – compounds A – D were identified, all of which have organometallic counterparts 2 – 5 . Only compound 2 has not been isolated as such, but the trapping of 2a in Wittig‐type reactions with carbonyl compounds to give the corresponding α‐chloroalkenyl isocyanide complexes proves its intermediary existence 1. As metallo‐nitrile ylides, capable of undergoing [3+2] cycloadditions, compounds 2 and 5 (after deprotonation) were of particular interest, the more as our synthetic access to 5 [and Cr(CO) 5 CNCHPPh 3 ] so far required several tricky steps through free functional isocyanides lacking metal stabilization [11, 12].…”

Section: Introductionmentioning

confidence: 99%

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Reactions of “in‐Situ” Generated Cr(CO)₅CN–C(Cl)–PR₃ (R = Ph, NMe₂) with Potential Dipolarophiles. New Examples of [3+2] Cycloadditions with Concomitant Interligand CC Bond Formation [1]

Ahn

Langenhahn

Sperber

et al. 2010

Zeitschrift anorg allge chemie

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The highly functional chromio nitrile ylides Cr(CO)5C≡N–C(Cl)–PR3 (R = Ph, NMe2) (2a, b) form readily in mixtures of Cr(CO)5CNCCl3 (1) with the respective phosphanes. Their reactions without isolation with the acylating agent Cr(CO)5CN(C=O)Ar (Ar = C6H4‐p‐NO2), MeO2CC≡CCO2Me, ketones (R2C=O, R = Me, Et; 2R = 9‐fluorenediyl) and phenyl isocyanate to give the Cl/COAr‐substitution‐ (6a), alkyne insertion‐ (10) and [3+2] cycloaddition products (13, 14) are described. Formation of the latter is accompanied by an interligand CC coupling with loss of P(NMe2)3 and OP(NMe2)3 (after hydrolysis). Their reactions are compared with those of the parent compounds LnMCN–C(H)–PPh3.

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“…[573] A corresponding interligand C=C bond formation to give 133 has been observed in [3+2]-cycloadditions with ketones or phenyl isocyanate of the new metallo nitrile ylides 132 generated 'in situ' from Cr(CO) 5 CNCCl 3 and PPh 3 or P(NMe 2 ) 3 , respectively. [580] The chemistry of metallo nitrile imines, in contrast, is based merely on the single mono-deprotonated isodiazomethane complex 121 containing the 16- …”

Section: [3+2]-cycloaddition Reactions With Organic Dipolarophilesmentioning

confidence: 99%

Azide Chemistry – An Inorganic Perspective, Part II^[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

Fehlhammer

Beck

2015

Zeitschrift anorg allge chemie

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Abstract. In whatever state of bonding -whether covalent to an organic residue or a heteroatom, or polar to ionic in contact with a metal -the azide moiety N 3 is characterized by its high potential of reactivity which essentially manifests itself in two basic processes: the elimination of dinitrogen and the entry into 1,3-dipolar cycloadditions with suitable dipolarophiles, the latter of which clearly predominates the chemistry of azide, also that of its metal compounds. In a preceding review entitled "Part I -Metal Azides: Overview, General Trends and Recent Developments" which was meant to lay the foundations for the present paper, these and other reactions have already been touched upon. The present review -Part II -now focusses in great detail on the formation of five-membered heterocyclestetrazol(at)es, triazol(at)es, triazolin(at)es, thiatriazol(at)es, etc. as well as various consecutive products -from azide and nitriles, isocyanides, alkynes, alkenes and heteroallenes (CS 2 , RN=C=S) in the ligand sphere of the metal. Generally, these [3+2]-cycloadditions are found to CONTENTS

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Reactions at the coordinated trichloromethyl isocyanide. Part VII. α-Chloroalkenylisocyanide versus oxazolin-2-ylidene(ato) complex formation

Cited by 7 publications

References 31 publications

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Reactions of “in‐Situ” Generated Cr(CO)₅CN–C(Cl)–PR₃ (R = Ph, NMe₂) with Potential Dipolarophiles. New Examples of [3+2] Cycloadditions with Concomitant Interligand CC Bond Formation [1]

Azide Chemistry – An Inorganic Perspective, Part II^[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

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Reactions at the coordinated trichloromethyl isocyanide. Part VII. α-Chloroalkenylisocyanide versus oxazolin-2-ylidene(ato) complex formation

Cited by 7 publications

References 31 publications

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Metal-induced tautomerization of oxazole and thiazole molecules to heterocyclic carbenes

Reactions of “in‐Situ” Generated Cr(CO)5CN–C(Cl)–PR3 (R = Ph, NMe2) with Potential Dipolarophiles. New Examples of [3+2] Cycloadditions with Concomitant Interligand CC Bond Formation [1]

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

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Reactions of “in‐Situ” Generated Cr(CO)₅CN–C(Cl)–PR₃ (R = Ph, NMe₂) with Potential Dipolarophiles. New Examples of [3+2] Cycloadditions with Concomitant Interligand CC Bond Formation [1]

Azide Chemistry – An Inorganic Perspective, Part II^[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems