Photolyse de melanges de pentyne-3one-2 et de tetramethylethylene dans C 6 H 6 conduisant aux cis- et trans-ethylidene-4 methylene-5 tetramethyl-2,2,3,3tetrahydrofuranne se transposant envinyldihydrofuranne et en oxetanne。Mecanisme: mise en jeu de carbenes
Regiochemistry and stereochemistry of intramolecular [2+2] photocycloaddition of carbon-carbon double bonds to cyclohexenones
摘要:
The intramolecular [2 + 2] photocycloaddition mechanism of alkenes tethered by a three-methylene chain to cyclohexenones has been studied. It was found that the reversion from a 1,4-diradical intermediate to starting material is slow relative to the rate of photoadduct formation. Only ''straight'' closure was observed in the systems studied. For compounds 1-3 and 5, the assumption that the first bond is formed between the beta-carbon of the enone and C-4' leading to a 1,4-diradical is supported. For the formation of compounds 6-11, possible mechanisms are discussed.
[EN] TUBULYSIN ANALOGS AND METHODS<br/>[FR] ANALOGUES DE TUBULYSINE ET PROCÉDÉS ASSOCIÉS
申请人:ENDOCYTE INC
公开号:WO2017031209A1
公开(公告)日:2017-02-23
The present disclosure relates to tubulysin derivatives and methods for making the same. The disclosure also relates to the use of such tubulysin derivatives in the preparation of drug conjugates of tubulysins.
Steric effects in intramolecular [2+2] photocycloaddition of CC double bonds to cyclohexenones.
作者:D. Becker、N. Haddad
DOI:10.1016/s0040-4020(01)80336-7
日期:1993.1
The effect of substituents on the mode of approach and the endo/exo ratio in intramolecular [2+2] photocycloaddition reactions were studied.
研究了取代基对分子内[2 + 2]光环加成反应中接近方式和内/外比的影响。
Direct Access to Versatile Electrophiles via Catalytic Oxidative Cyanation of Alkenes
作者:De-Wei Gao、Ekaterina V. Vinogradova、Sri Krishna Nimmagadda、Jose M. Medina、Yiyang Xiao、Radu M. Suciu、Benjamin F. Cravatt、Keary M. Engle
DOI:10.1021/jacs.8b03704
日期:2018.7.5
discovery. Reactions that directly transform inexpensive chemical feedstocks into versatile carbon electrophiles would therefore be highly enabling. Herein, we report the catalytic, regioselective oxidative cyanation of conjugated and nonconjugated alkenes using a homogeneous copper catalyst and a bystanding N-F oxidant to furnish branched alkenyl nitriles that are difficult to prepare using existing methods
that attractive dispersion forces may be responsible for a change of the binding mode. The catalytic [2+2] photocycloaddition was shown to proceed on the triplet hypersurface with a quantum yield of 0.05. The positive effect of Lewis acids on the outcome of a given intramolecular [2+2] photocycloaddition was illustrated by optimizing the key step in a concise total synthesis of the sesquiterpene (±)‐italicene
Coupling Reaction of Enol Derivatives with Silyl Ketene Acetals Catalyzed by Gallium Trihalides
作者:Yoshihiro Nishimoto、Yuji Kita、Hiroki Ueda、Hiroto Imaoka、Kouji Chiba、Makoto Yasuda、Akio Baba
DOI:10.1002/chem.201602150
日期:2016.8.8
cross‐coupling reaction between enolderivatives and silyl ketene acetals catalyzed by GaBr3 took place to give the corresponding α‐alkenyl esters. GaBr3 showed the most effective catalytic ability, whereas other metal salts such as BF3⋅OEt2, AlCl3, PdCl2, and lanthanide triflates were not effective. Various types of enol ethers and vinyl carboxylates as enolderivatives are amenable to this coupling