Arylcyclopropane photochemistry. Unusual aromatic substituent effects on the photochemical rearrangement of (2-arylcyclopropyl)methyl acetates to 1-arylhomoallyl acetates
Substituent effects on the13C NMR spectra of ethylcis- andtrans-2-(p-substituted-phenyl)-1-cyclopanecarboxylates
作者:Yoshiaki Kusuyama、Kenjiro Tokami
DOI:10.1002/mrc.1260300415
日期:1992.4
13C NMR spectra were measured for a series of ethyl cis- and trans-2-(p-substituted - phenyl) - 1 - cyclopropanecarboxylates. The effects of the para substituents and the geometry on the chemical shifts are discussed.
A Heteroleptic Dirhodium Catalyst for Asymmetric Cyclopropanation with α‐Stannyl α‐Diazoacetate. “Stereoretentive” Stille Coupling with Formation of Chiral Quarternary Carbon Centers
作者:Fabio P. Caló、Alois Fürstner
DOI:10.1002/anie.202004377
日期:2020.8.10
The heteroleptic dirhodium paddlewheel catalyst 7 with a chiral carboxylate/acetamidate ligand sphere is uniquely effective in asymmetric [2+1] cycloadditions with α‐diazo‐α‐trimethylstannyl (silyl, germyl) acetate. Originally discovered as a trace impurity in a sample of the homoleptic parent complex [Rh2((R )‐TPCP)4] (5 ), it is shown that the protic acetamidate ligand is quintessential for rendering
Cyclopropanation of alkenes with metallocarbenes generated from monocarbonyl iodonium ylides
作者:Tristan Chidley、Graham K. Murphy
DOI:10.1039/c8ob02636j
日期:——
Reacting Wittigreagents and the hypervalent iodine reagent iodosotoluene, in the presence of 10 mol% Cu(tfacac)2 and 5 equiv. of alkene, results in a novel cyclopropanation reaction. The reagent combination is believed to generate a transient monocarbonyliodoniumylide (MCIY) in situ, which can be intercepted by the copper catalyst to give a metallocarbene. Both ester and ketone derived phosphoranes
One-pot approach for the synthesis of trans-cyclopropyl compounds from aldehydes. Application to the synthesis of GPR40 receptor agonists
作者:Michaël Davi、Hélène Lebel
DOI:10.1039/b810708d
日期:——
A novel multicatalytic one-pot process providing trans-cyclopropyl compounds from corresponding aldehydes has been developed and applied to the synthesis of GPR40 small molecule agonists.
addition of the very reactive metallacarbene intermediate in an early transition state to the substrate alkene is concerted but strongly asynchronous, with substantial cationic character on one alkene carbon in the neighborhood of the transition state. Evidence from isotope effects and Hammett studies supports the nature of the transition state. Formation of a metallacyclobutaneintermediate by a [2+2] addition