Pd-catalyzed carbonylation,as an efficient synthetic approach to the installation of carbonyl groups in organic compounds,has been one of the most important research fields in the past decade.Although elegant reaction...Pd-catalyzed carbonylation,as an efficient synthetic approach to the installation of carbonyl groups in organic compounds,has been one of the most important research fields in the past decade.Although elegant reactions that allow highly selective carbonylations have been developed,straightforward routes with improved reaction activity and broader substrate scope remain long-term challenges for new practical applications.Here,we show a new type of synergistic Cu/Pd-catalyzed carbonylation reaction using alcohols and dioxgen as the carbonyl sources.A broad range of aryl iodides and alcohols are compatible with this protocol.The reaction is concise and practical due to the ready availability of the starting materials and the scalability of the reaction.In addition,the reaction affords lactones and lactams in an intermolecular fashion.Moreover,DFT calculations have been performed to study the detailed mechanisms.展开更多
针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于...针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于不同纬度区域CU四叉树深度的分布特性和相邻CU的相关性,对当前CU的划分模式进行提前终止决策;利用梯度差异评估当前CU纹理特性,跳过冗余的水平或垂直划分模式。针对纹理模糊CU,通过纬度采样权重加权的二次比较,判断是否跳过垂直划分模式;利用二维哈尔小波变换系数评估当前CU子块间的差异,判断是否跳过三叉树划分模式。实验结果表明,在全帧内模式下,与VVC官方测试平台相比,所提算法能节省43.85%的编码时间,码率仅增加0.85%,视频质量没有明显下降。展开更多
基金supported by the Science Foundation for Distinguished Young Scholars for Guangdong Province(2020B1515020026)the Science and Technology Program of Guangzhou(202103000089)+6 种基金the Innovation Team Project of Universities in Guangdong Province(2020KCXTD009)the Scientific Research Projects for Key Disciplines of Guangdong Province(2019-GDXK-0009)the Key Projects of Social Welfare and Basic Research of Zhongshan City(2020B2007)the Innovation and Strong School Project of Guangdong Pharmaceutical University(2018KQNCX131)Guangdong Cosmetics Engineering&Technology Research CenterProvincial Experimental Teaching Demonstration Center of Chemistry&Chemical EngineeringSpecial Funds of Key Disciplines Construction from Guangdong and Zhongshan Cooperating。
文摘Pd-catalyzed carbonylation,as an efficient synthetic approach to the installation of carbonyl groups in organic compounds,has been one of the most important research fields in the past decade.Although elegant reactions that allow highly selective carbonylations have been developed,straightforward routes with improved reaction activity and broader substrate scope remain long-term challenges for new practical applications.Here,we show a new type of synergistic Cu/Pd-catalyzed carbonylation reaction using alcohols and dioxgen as the carbonyl sources.A broad range of aryl iodides and alcohols are compatible with this protocol.The reaction is concise and practical due to the ready availability of the starting materials and the scalability of the reaction.In addition,the reaction affords lactones and lactams in an intermolecular fashion.Moreover,DFT calculations have been performed to study the detailed mechanisms.
文摘针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于不同纬度区域CU四叉树深度的分布特性和相邻CU的相关性,对当前CU的划分模式进行提前终止决策;利用梯度差异评估当前CU纹理特性,跳过冗余的水平或垂直划分模式。针对纹理模糊CU,通过纬度采样权重加权的二次比较,判断是否跳过垂直划分模式;利用二维哈尔小波变换系数评估当前CU子块间的差异,判断是否跳过三叉树划分模式。实验结果表明,在全帧内模式下,与VVC官方测试平台相比,所提算法能节省43.85%的编码时间,码率仅增加0.85%,视频质量没有明显下降。
