82352-44-1Relevant academic research and scientific papers
Nickel(II)-Catalyzed Asymmetric Propargyl and Allyl Claisen Rearrangements to Allenyl- and Allyl-Substituted β-Ketoesters
Liu, Yangbin,Hu, Haipeng,Zheng, Haifeng,Xia, Yong,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
supporting information, p. 11579 - 11582 (2016/02/19)
Highly efficient catalytic asymmetric Claisen rearrangements of O-propargyl β-ketoesters and O-allyl β-ketoesters have been accomplished under mild reaction conditions. In the presence of the chiral N,N′-dioxide/NiII complex, a wide range of allenyl/allyl-substituted all-carbon quaternary β-ketoesters was obtained in generally good yield (up to 99 %) and high diastereoselectivity (up to 99:1 d.r.) with excellent enantioselectivity (up to 99 % ee).
REGIOCHEMICAL DIVERSITY IN ALLYLIC ALKYLATIONS VIA MOLYBDENUM CATALYSTS
Trost, Barry M.,Lautens, Mark
, p. 4817 - 4840 (2007/10/02)
The use of molybdenum as a template to control regioselectivity in allylic alkylations is explored.The feasibility of performing allylic alkylations with preformed ?-allylmolybdenum comlplexes is established.As in palladium reactions, addition of excess phosphine has a profound effect on the rate these reactions.A catalytic reaction based upon molybdenum hexacarbonyl is developed.Using malonate anion, excellent regioselectivity for attack at the more substituted end of an allyl system regardless of the positional identity of the initial leaving group exists.With β-ketoesters, substrates which possess a secondary and a primary carbon in the allyl unit lead to preferential attack at the secondary carbon.However, substrates that possess a tertiary and a primary carbon at the termini lead to attack at the primary carbon.Anions derived from substituted malonates and 1,3-diketones lead to substitution at the less substituted position of allyl systems.The presence of strongly electron withdrawing substituents has little effect on these orientational blases.Mechanistic implications of these results are discussed.
