1380940-71-5Relevant academic research and scientific papers
Reaction of frustrated lewis pairs with ketones and esters
Xu, Bao-Hua,Yanez, Raul Alfonso Adler,Nakatsuka, Hiroshi,Kitamura, Masato,Froehlich, Roland,Kehr, Gerald,Erker, Gerhard
, p. 1347 - 1356 (2012)
The frustrated Lewis pair (FLP) Mes2PCH2CH 2B(C6F5)2 (1) reacts with an enolizable conjugated ynone by 1,4-addition involving enolate tautomerization to give an eight-membered zwitterionic heterocycle. The conjugated endione PhCO-CH=CH-COPh reacts with the intermolecular FLP tBu3P/B(C 6F5)3 by a simple 1,4-addition to an enone subunit. The same substrate undergoes a more complex reaction with the FLP 1 that involves internal acetal formation to give a heterobicyclic zwitterionic product. FLP 1 reacts with dimethyl maleate by selective overall addition to the C=C double bond to give a six-membered heterocycle. It adds analogously to the triple bond of an acetylenic ester to give a similarly structured six-membered heterocycle. The intermolecular FLP P(o-tolyl)3/B(C6F 5)3 reacts analogously with acetylenic ester by trans-addition to the carbon-carbon triple bond. An excess of the intermolecular FLP tBu3P/B(C6F5)3, which contains a more nucleophilic phosphane, reacts differently with acetylenic ester examples, namely by O-C(alkyl) bond cleavage to give the {R-CO 2[B(C6F5)3]2 -}[alkyl-PtBu3+] salts. Simple aryl or alkyl esters react analogously by using the borane-stabilized carboxylates as good leaving groups. All essential products were characterized by X-ray diffraction. Copyright
