Palladium-catalyzed C-C Bond Cleavage Of Furfuryl Alcohols For Access To ?-Arylfurans

With the continuous exploitation and irrational utilization of petrochemical resources,the energy crisis and environmental pollution have become increasingly serious.It is recognized that a sustainable future of the chemical industry requires feedstocks based on renewable materials rather than steadily depleting fossil resources.Inability to effectively transform carbohydrates derived from plants into a variety of fine chemical products is a major barrier towards this challenging goal.In recent years,the high value-added conversion of furfuryl alcohol has provided a sustainable source for some pharmaceutical intermediates and industrial feedstocks.We developed a simple,practical reaction for ?-arylation of furfuryl alcohols,which preferably realizes the sustainable utilization of resources and provides a novel synthetic route for the synthesis of 2,5-diarylfurans.This thesis mainly includes the following two parts:Part ? We realized a novel palladium-catalyzed oxidative coupling reaction between industrially available arylboronic acids and(5-arylfuran-2-yl)methanols in the presence of oxygen as the terminal oxidant,and with a C–C bond cleavage which may be induced by aromatization of furan oxonium ion.This protocol represents the first example of C–C bond activation of primary alcohols,which is sharply different from secondary or tertiary alcohols in the previous reports.Part ? We prepared a TBS-protected furfuryl alcohol from industrially mass-produced 5-hydroxymethylfurfural(HMF)by selective reduction.Subsequently,a variety of TBS-protected(5-arylfuran-2-yl)methanols were synthesized by a palladium-catalyzed oxidative arylation of TBS-protected furfuryl alcohol.After being deprotected,TBS-protected(5-arylfuran-2-yl)methanols can transform into 2,5-diarylfurans by further oxidative coupling with boronic acids.This reaction not only provides a novel synthetic strategy for the synthesis of asymmetric 2,5-diarylfurans,but also opens a new avenue for the high value-added transformation of HMF into useful 2,5-diarylfurans.Simultaneously,compared with conventional synthetic methods of 2,5-diarylfurans,this method is more environmentally friendly and with higher atom economy as it directly avoids the use of aryl halides or organotin reagents.