Trans-Selective Olefination of Carbonyl Compounds by Low-Valent Titanium-Mediated Dehydroxybenzotriazolylation
摘要:
Lithiation with n-butyllithium of a variety of benzotriazole derivatives 1a-f and 5a-d, all containing a proton alpha to the benzotriazolyl moiety, gave anions which underwent addition to aliphatic, aromatic, and alpha,beta-unsaturated aldehydes and cyclic and acyclic ketones. The resultant N-(beta-hydroxyalkyl)benzotriazole derivatives 3a-m, 6a-g, 9a-d, and 10a were dehydroxybenzotriazolylated when treated with low-valent titanium to give alkenes 4a-m, dienes 7a-j, and triene 11a, with selectivity for the trans isomers without separation of diastereoisomeric intermediates. This method offers an alternative to the three most frequently used methods for the formation of alkenes from carbonyl compounds-the Wittig, Peterson, and Julia reactions-especially in the formation of tri- and tetrasubstituted alkenes.
Site-Selective and Stereoselective <i>trans</i>-Hydroboration of 1,3-Enynes Catalyzed by 1,4-Azaborine-Based Phosphine–Pd Complex
作者:Senmiao Xu、Yuanzhe Zhang、Bo Li、Shih-Yuan Liu
DOI:10.1021/jacs.6b09759
日期:2016.11.9
A concise synthesis of monobenzofused 1,4-azaborine phosphine ligands (Senphos) is described. These Senphos ligands uniquely support Pd-catalyzed trans-selective hydroboration of terminal and internal 1,3-enynes to furnish corresponding dienylboronates in high efficiency and diastereoselectivity. X-ray structural analysis of the Senphos-Pd(0) complex reveals a κ2-P-η2-BC coordinationmode, and this
Hemilabile P,N-Ligand-Assisted Gold-Catalyzed Heck Reaction of Aryl and Styryl Iodides with Styrenes
作者:Cunbo Wei、Lizhu Zhang、Zhonghua Xia
DOI:10.1021/acs.orglett.3c02244
日期:2023.9.22
Heck reaction of aryl and styryl iodides with styrenes was developed. The hemilabile P,N-ligand-assisted gold-catalyzed C(sp2)–C(sp2) cross-coupling can synthesize stilbenes and bistyryl complexes, with good functional-group tolerance and mild conditions. The elementary organometallic steps of migratory insertion and β-hydride elimination might be involved in this ligand-enabled Au(I)/Au(III)-catalyzed
Ag+-catalyzed rearrangements. XIV. Influence of structural features of the course of bicyclo[1.1.0]butane rearrangements catalyzed by silver(I) ion
作者:Leo A. Paquette、Richard P. Henzel、Stanley E. Wilson
DOI:10.1021/ja00777a021
日期:1972.11
Iron-Promoted Elimination of β-Thioalkoxy Alcohols. Olefination by Coupling of a Carbonyl Group with a Dithioacetal
作者:Li-Fu Huang、Chih-Wei Chen、Tien-Yau Luh
DOI:10.1021/ol701579f
日期:2007.8.1
Treatment of propargylic dithiolanes with (BuLi)-Bu-n followed by a carbonyl electrophile yields the corresponding propargylic dithioacetals. Upon treatment with 1 equiv of Fe(acac)(3) and excess MeMgI, elimination of SR and OH moieties from 8 affords the corresponding olefins in satisfactory yield. Benzylic dithioacetals behave similarly. The reaction can be considered an alternative of McMurry coupling of two different carbonyl equivalents.