5713-61-1Relevant articles and documents
Vanishing microwave effects: Influence of heterogeneity
Dressen, Mark H. C. L.,Van De Kruijs, Bastiaan H. P.,Meuldijk, Jan,Vekemans, Jef A. J. M.,Hulshof, Lumbertus A.
, p. 865 - 869 (2007)
A consistent setup of experiments has been conducted to demonstrate an enhanced reaction rate under microwave irradiation as compared to conventional heating, i.e. a real microwave effect It was found that addition of a cosolvent, diminishing the heterogeneous character of the reaction mixture, greatly reduced the microwave effect. This was demonstrated by two examples; selective mono-urea formation and racemization of an N-acetylamino acid. Furthermore, formation of a Grignard reagent was accelerated under MW irradiation by electrostatic etching of the metal surface. The microwave effect observed in these reactions seems to rely on heterogeneity and specific interactions on the solid-liquid interface. Basic understanding of these findings is crucial for scaling up microwave assisted processes.
Stereodivergent Construction of Vicinal Acyclic Quaternary-Tertiary Carbon Stereocenters by Michael-Type Alkylation of α,α-Disubstituted N- tert-Butanesulfinyl Ketimines
Liu, Hui,Lu, Chong-Dao,Yao, Yun,Yisimayili, Nuermaimaiti
supporting information, p. 7450 - 7455 (2021/10/02)
Vicinal quaternary-tertiary carbon stereocenters were constructed with excellent stereoselectivity via aza-enolization of enantioenriched acyclic N-tert-butanesulfinyl ketimines bearing two sterically similar α-linear alkyl substituents followed by conjugate addition to nitroalkenes. Further changes of the absolute configuration of the sulfinyl group and/or the α-stereocenter in the ketimine allowed the facile stereodivergent synthesis of all four diastereomers of the Michael-type alkylation adducts. This reaction is a successful example of acyclic stereocontrol based on stereoselective α-deprotonation for the formation of fully substituted aza-enolates from ketone derivatives.
Palladium-catalyzed aerobic oxidative double allylic C-H oxygenation of alkenes: A novel and straightforward route to α,β-unsaturated esters
Yang, Wanfei,Chen, Huoji,Li, Jianxiao,Li, Chunsheng,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 9575 - 9578 (2015/06/08)
A mild tandem oxidative functionalization of allyl aromatic hydrocarbons was accomplished using the catalytic system of Pd(OAc)2/DMA under 1 atm O2. The green twofold C-O bond formation involving double allylic C-H oxygenation unlocks opportunities for markedly different synthetic strategies. Moreover, the reaction affords aryl α,β-unsaturated esters directly from readily available terminal olefins in moderate to good yields with excellent chemo- and stereoselectivities.
