Asymmetric Synthesis of a New Salen Type-titanium Complex as the Catalyst for Asymmetric Trimethylsilylcyanation of Aldehydes
作者:Zheng-Chang Lin、Chinpiao Chen
DOI:10.1002/jccs.201000101
日期:2010.8
This work describes the asymmetric synthesis of a new salen‐type ligand via a Diels‐Alder reaction and Curtius rearrangement. The ligand with a norbornane skeleton was used in the trimethylsilylcyanation of aldehydes, but the enantioselectivity was 55%ee. The norborane skeleton was cleaved to destroy this rigidity, and the eanatioselectivity was thereby increased to 85%ee.
The vanadium(V)(salalen) complex prepared in situ from the corresponding vanadium(IV) complex 4 under aerobic conditions was found to be an excellent catalyst for asymmetric transcyanation of aliph...
Room-temperature synthesis of enantioenriched non-protected cyanohydrins using acetone cyanohydrin as the cyanide source was achieved by V(salalen) catalyst. Aliphatic aldehydes underwent the cyanation with 89–95% ee in the presence of only 0.2–0.4 mol% catalyst. Aromatic cyanohydrins were also obtained in high enantiomeric excesses under modified conditions.
Ester Synthesis in Water: <i>Mycobacterium smegmatis</i>
Acyl Transferase for Kinetic Resolutions
作者:Nicolas de Leeuw、Guzman Torrelo、Carolin Bisterfeld、Verena Resch、Luuk Mestrom、Emanuele Straulino、Laura van der Weel、Ulf Hanefeld
DOI:10.1002/adsc.201701282
日期:2018.1.17
The acyl transferase from Mycobacterium smegmatis (MsAcT) catalyses transesterification reactions in aqueous media because of itshydrophobic active site. Aliphatic cyanohydrin and alkyne esters can be synthesised in water with excellent and strikingly opposite enantioselectivity [(R);E>37 and (S);E>100, respectively]. When using this enzyme, the undesired hydrolysis of the acyl donor is an important
Asymmetric addition of trimethylsilyl cyanide to aldehydes promoted by chiral polymeric vanadium(V) salen complex as an efficient and recyclable catalyst
作者:Noor-ul H. Khan、Santosh Agrawal、Rukhsana I. Kureshy、Sayed H.R. Abdi、Vishal J. Mayani、Raksh V. Jasra
DOI:10.1016/j.tetasy.2006.09.024
日期:2006.10
The asymmetric addition of trimethylsilyl cyanide to various aldehydes catalyzed by efficient new vanadyl polymeric salen complexes having 12 repeating salen units was investigated at room temperature. An excellent yield of the trimethylsilylether of cyanohydrins (up to 98%) with high chiral induction (96%) in case of 2-methylbenzaldehyde was achieved in 18 h. The catalyst recovered four times with