38177-56-9Relevant articles and documents
Zur Umsetzung von Bis(alkinyl)-Titanocenen mit übergangsmetall-Verbindungen von Cu(II), Pd(II), Pt(II), Fe(III) und Au(III)
Frosch,Back,K?hler,Lang
, p. 226 - 232 (2000)
The reaction behaviour of the bis(alkynyl) titanocenes [Ti](CCR1)(CCR2) {[Ti]=(η5-C5H4SiMe3) 2Ti; 1: R1=R2=Fc, Fc=(η5-C5H4)Fe(η5-C 5H5); 5a: R1=R2=SiMe3; 5b: R1=R2=C6H5; 5c: R1=SiMe3, R2=C6H5} towards MX2 (M=Pd, Pt; X=Cl; M=Cu; X=Cl, Br, OAc, acac) and MCl3 (M=Fe, Au) is described. All reactions are dominated by redox processes. Generally, the reaction of 1 or 5a-5c with AuCl3 or MCl2 (M=Cu, Pd, Pt) produces the titanocene dichloride [Ti]Cl2 (3a) along with the corresponding butadiynes R1CC-CCR2 (4: R1=R2=Fc; 7a: R1=R2=SiMe3; 7b: R1=R2=C6H5; 7c: R1=SiMe3, R2=C6H5) and M(0) (M=Cu, Au, Pd, Pt). As key intermediates the heterobimetallic tweezer complexes {[Ti](CCR1)(CCR2)}MCl2 (M=Cu, Pd, Pt) are formed. These reactions are strongly solvent dependent. While {[Ti](CCFc)2}CuCl2 (2) is readily formed as the main product when 1 is reacted with CuCl2 in diethyl ether, it is found that 2 affords 3a, 4 and Cu(0) on prolonged stirring in tetrahydrofuran. In contrast, complexes 5a-5c produce with equimolar amounts of CuX2 (X=Cl, Br) the compounds [Ti]X2 (3a: X=Cl, 3b: X=Br), R1CC-CCR2 (7a: R1=R2=SiMe3; 7b: R1=R2=C6H5; 7c: R1=SiMe3, R2=C6H5), {[Ti](CCR1)(CCR2)}CuX (6a: R1=R2=SiMe3, X=Cl; 6b: R1=R2=SiMe3, X=Br; 6c: R1=R2=C6H5, X=Cl; 6d: R1=SiMe3; R2=C6H5, X=Cl) as well as 1/n[CuX]n (X=Cl, Br). However, when 5a is treated with Cu(OAc)2 or Cu(acac)2 in a 1:1 ratio, heterobimetallic {[Ti](CCSiMe3)2}CuX (6e: X=OAc, 6f: X=acac) is the only isolated species. Possible mechanisms for the reactions presented are described.
Total Synthesis of (S)-(-)-(E)-15,16-Dihydrominquartynoic Acid: A Highly Potent Anticancer Agent
Gung, Benjamin W.,Kumi, Godwin
, p. 3488 - 3492 (2004)
The conjugated entriyne natural product, (S)-(E)-15, 16-dihydrominquartynoic acid (1), is synthesized in five linear steps and 30% overall yield from the known aldehyde 11. The key step is a one-pot in situ desilylation/Cadiot-Chodkiewicz coupling reaction affording the entriyne unit. The bromoalkyne 6 with ω-carboxylic acid group was found to undergo a copper-catalyzed cross-coupling reaction producing the desired diyne intermediate 10, while the corresponding ω-ester bromoalkyne 14 failed to couple with triethylsilylacetylene under a variety of conditions.
Rh(III)-Catalyzed [3 + 2] Spirocyclization of 2 H-Imidazoles with 1,3-Diynes for the Synthesis of Spiro-[imidazole-indene] Derivatives
Luo, Yi,Liu, Hao,Zhang, Jing,Liu, Man,Dong, Lin
supporting information, p. 7604 - 7608 (2020/10/09)
An effective strategy to synthesize spirocyclic compounds, [imidazole-4,1′-indene], has been efficaciously developed relied on Rh(III)-catalyzed [3 + 2] spirocyclization of 2H-imidazoles and 1,3-diynes with excellent chemselectivity and regioselectivity.
Iron(II)-Based Metalloradical Activation: Switch from Traditional Click Chemistry to Denitrogenative Annulation
Roy, Satyajit,Khatua, Hillol,Das, Sandip Kumar,Chattopadhyay, Buddhadeb
supporting information, p. 11439 - 11443 (2019/07/17)
A unique concept for the intermolecular denitrogenative annulation of 1,2,3,4-tetrazoles and alkynes was discovered by using a catalytic amount of Fe(TPP)Cl and Zn dust. The reaction precludes the traditional, more favored click reaction between an organic azide and alkynes, and instead proceeds by an unprecedented metalloradical activation. The method is anticipated to advance access to the construction of important basic nitrogen heterocycles, which will in turn enable discoveries of new drug candidates.
