68062-36-2Relevant academic research and scientific papers
Reactions between Benzocyclobutenone Tricarbonylchromium Complexes and Lithium Dialkylphosphides: A New Route to Isochromanones
Schnebel, Matthias,Weidner, Ingo,Wartchow, Rudolf,Butenschoen, Holger
, p. 4363 - 4372 (2007/10/03)
The reaction between rac-(benzocyclobutenone)tricarbonylchromium (rac-1) and lithium diisopropylphosphide (LDP) or lithium di-tert-butylphosphide, unlike its reaction with lithium diisopropylamide (LDA), results in a distal ring-opening, with formation of acylphosphane derivatives. The tricarbonylchromium complex rac-6 of 2-methylbenzoyldiisopropylphosphane has been structurally characterized. The reaction proceeds through the corresponding benzylic anion intermediate, which was shown to react with ketones or aldehydes with formation of isochromanone derivatives. This indicates that a dialkylphosphide is a much better leaving group than an amide. The availability of 1 in enantiomerically pure form inspired an inspection of the diastereoselectivity of the cyclization with aldehydes. It was found that the reaction between the intermediate and benzaldehyde took place with complete diastereoselectivity, thus establishing a route to enantiomerically pure 3-phenyhsochromanone. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
