36681-70-6Relevant academic research and scientific papers
Carbocation Catalysis: Oxa-Diels-Alder Reactions of Unactivated Aldehydes and Simple Dienes
El Remaily, Mahmoud Abd El Aleem Ali Ali,Naidu, Veluru Ramesh,Ni, Shengjun,Franzén, Johan
, p. 6610 - 6614 (2015)
The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in the oxa-Diels-Alder reaction of various unactivated aromatic and aliphatic aldehydes and simple unactivated dienes, such as isoprene and 2,3-dimethylbutadiene. The transformation proceeds smoothly to give 3,6-dihydropyrane adducts in high to moderate yields with catalyst loadings down to 1.0 mol-% under mild reaction conditions. In contrast to most previously reported strategies, this protocol does not require substrate functional group activation, neither by electron-deficient aldehydes (2-oxo aldehydes) or electron-rich dienes (methoxy or amino-butadiene).
Cationic iron(III) porphyrin-catalyzed [4 + 2] cycloaddition of unactivated aldehydes with simple dienes
Fujiwara, Kyohei,Kurahashi, Takuya,Matsubara, Seijiro
supporting information; experimental part, p. 5512 - 5515 (2012/05/20)
Cationic iron(III) porphyrin was found to be an efficient catalyst for the highly chemoselective hetero-Diels-Alder-type reaction of aldehydes with 1,3-dienes. The catalyzed process did not require the use of electron-deficient aldehydes such as glyoxylic acid derivatives or activated electron-rich 1,3-dienes such as Danishefsky's diene and Rawal's diene. The high functional group tolerance and robustness of the catalyst were demonstrated. Further, the potential utility of the catalyst was demonstrated by performing the cycloaddition in the presence of water and by carrying out cycloaddition of an unactivated ketone such as cyclohexanone with a diene.
