In situ generation of vinyl allenes and its applications to one-pot assembly of cyclohexene, cyclooctadiene, 3,7-nonadienone, and bicyclo[6.4.0]dodecene derivatives with palladium-catalyzed multicomponent reactions |
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Authors: | Lee Phil Ho Lee Kooyeon Kang Youngjin |
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Institution: | Department of Chemistry, Kangwon National University, Chunchon, Republic of Korea. phlee@kangwon.ac.kr |
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Abstract: | A novel tandem Pd-catalyzed cross-coupling and 4 + 4] cycloaddition sequence allows the rapid synthesis of eight-membered carbocycles starting from alpha-bromovinyl arenes and propargyl bromides in one reaction vessel. It is noteworthy that four components are assembled into one molecule via this procedure. In contrast to alpha-bromovinyl arenes, alpha-bromovinyl alkanes afforded tandem cross-coupling and homo 4 + 2] cycloaddition products. Subjecting an equimolar mixture of alpha-bromostyrene and 2-bromo-1-octene to propargyl bromides furnished the tandem Pd-catalyzed cross-coupling and hetero 4 + 2] cycloaddition product. Exposure of equimolar mixtures of alpha-bromovinyl arenes to allenylindium resulted in tandem a Pd-catalyzed cross-coupling and hetero 4 + 4] cycloaddition products. Synthesis of vinylallene from the reaction of vinyl triflate with allenylindium followed by Pd-catalyzed carbon monoxide insertion reaction gave the corresponding 3,7-nonadienone product via tandem Pd-catalyzed cross-coupling and 4 + 4 + 1] annulation. Tandem Pd-catalyzed cross-coupling, 4 + 4] cycloaddition, and 4 + 2] cycloaddition provided the rapid synthesis of bicyclo6.4.0]dodecene derivatives starting from alpha-bromovinyl arenes, propargyl bromides, and dienophiles in one operation, in which five components were integrated into one molecule. |
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