Half-Sandwich Ruthenium Carbene Complexes Link<i>trans</i>-Hydrogenation and<i>gem</i>-Hydrogenation of Internal Alkynes
作者:Alexandre Guthertz、Markus Leutzsch、Lawrence M. Wolf、Puneet Gupta、Stephan M. Rummelt、Richard Goddard、Christophe Farès、Walter Thiel、Alois Fürstner
DOI:10.1021/jacs.8b00665
日期:2018.2.28
E-alkenes are formed by trans-delivery of the two H atoms of H2. A combinedexperimental and computational study now provides a comprehensive mechanistic picture: a metallacyclopropene (η2-vinyl complex) is primarily formed, which either evolves into the E-alkene via a concerted process or reacts to give a half-sandwich ruthenium carbene; in this case, one of the C atoms of the starting alkyne is converted
A Convergent Coupling Strategy for the Formation of Polycyclic Ethers: Stereoselective Synthesis of the BCDE Fragment of Brevetoxin A
作者:Michael T. Crimmins、Patrick J. McDougall、Kyle A. Emmitte
DOI:10.1021/ol051543m
日期:2005.9.1
has been completed. anti-Glycolate aldol, glycolate alkylation, and ring-closing metathesis reactions were employed as key bond-forming events. A convergent assembly strategy was employed that relied on a Horner-Wadsworth-Emmons union of two complex fragments. Subsequent cyclization and dehydration led to efficient generation of an intermediate endocyclic enolether, which was advanced to a tetracyclic
Facile methods for preparing diketide and triketide thioesters are disclosed. The resulting thioesters may be used as intermediates in the synthesis of desired polyketides, and may contain functional groups which ultimately reside in side chains on the resulting polyketide and thus can be used further to manipulate the polyketide so as form derivatives. The polyketides produced may also be tailored by glycosylation, hydroxylation and the like. New polyketides and their derivatives and tailored forms are thereby produced.
Stereoselective Synthesis of Quaternary Carbons via the Dianionic Ireland–Claisen Rearrangement
作者:Michael T. Crimmins、John D. Knight、Philip S. Williams、Yan Zhang
DOI:10.1021/ol5008422
日期:2014.5.2
α-methyl-β-hydroxy allylic esters has been developed that proceeds with high diastereoselectivity and provides products containing three contiguous stereogenic carbons, including a quaternary center. The potential utility of the rearrangement for complex molecule synthesis is also demonstrated.
Palladium‐Catalyzed Selective Reduction of Carbonyl Compounds
作者:Nabin Sarkar、Mamata Mahato、Sharanappa Nembenna
DOI:10.1002/ejic.202000310
日期:2020.6.23
the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT‐IR, and HRMS), including single‐crystal X‐ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1 –2 for the hydroboration of carbonyl compounds with pinacolborane