Photo-allylation and photo-benzylation of carbonyl compounds using organotrifluoroborate reagents
作者:Yutaka Nishigaichi、Takayuki Orimi、Akio Takuwa
DOI:10.1016/j.jorganchem.2009.08.011
日期:2009.11
Allyl- and benzyl-trifluoroborates can be applied to the photoreaction of carbonylcompounds to afford the corresponding alcoholic adducts in acceptable yields via a photo-induced single electron transfer pathway. The results were confirmed from the reaction selectivity and the negative free energy change for the electron transfer process.
In the photochemical reaction of allyl- and benzyltrimethylstannanes with unsymmetric α-diketones (PhCOCOR), the allylic group was introduced to the benzoyl carbon in high or excellent selectivity, whereas the acyl carbon was allylated either exclusively or predominantly under BF3-mediated reaction.
Chiral allylating reagents, readily generated in situ from tin(II) catecholate [SnII(O2C6H4)], allyl halides, chiral dialkyl tartrates, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), reacted smoothly with aldehydes or reactive ketones at −78 °C in the presence of a catalytic amount of copper salts to afford the corresponding optically active homoallyl alcohols. Allylation of aromatic aldehydes and pyruvates
手性烯丙基化试剂很容易从儿茶酚锡 (II) [SnII(O2C6H4)]、烯丙基卤化物、手性酒石酸二烷基酯和 1,8-二氮杂双环 [5.4.0] undec-7-烯 (DBU) 原位生成,反应平稳在催化量的铜盐存在下,在 -78 °C 下与醛或反应性酮反应,得到相应的光学活性高烯丙醇。本手性锡试剂对芳香醛和丙酮酸的烯丙基化反应以高产率 (81-99%) 和高对映选择性 (89-94%ee) 进行。此外,柠檬苹果酸二甲酯的两种对映异构体均由丙酮酸苄酯的烯丙基化产物制备。
Remarkable enhancement of photo-allylation of aromatic carbonyl compounds with a hypervalent allylsilicon reagent by donor molecules
作者:Yutaka Nishigaichi、Akira Suzuki、Akio Takuwa
DOI:10.1016/j.tetlet.2006.11.057
日期:2007.1
Photo-allylation of various aromaticcarbonylcompounds with a penta-coordinated allylsiliconate reagent was remarkably accelerated by the addition of a donor molecule. As the oxidation potential of the allylsiliconate was significantly decreased in the presence of a donor molecule, the more efficient photo-induced electrontransfer from the allylsiliconate to the excited substrate was enabled by the
Complete control of the rearrangement modes of enolates of .alpha.-allyloxy ketones: reversal from the [3,3]-Claisen to the [2,3]-Wittig pathway by the use of the metalated N,N-dimethylhydrazones