1、有机化学有机化学 Chinese Journal of Organic Chemistry ARTICLE *Corresponding author.E-mail: Received May 22,2022;revised July 25,2022;published online August 17,2022.Project supported by the National Natural Science Foundation of China(Nos.21822103,21820102003,91956201),the Program of Introducing Talents of
2、 Discipline to Universities of China(111 Program,No.B17019)and the Natural Science Foundation of Hubei Province(No.2017AHB047).国家自然科学基金(Nos.21822103,21820102003,91956201)、高等学校学科创新引智计划(111 计划,No.B17019)和湖北省自然科学基金(No.2017AHB047)资助项目.Chin.J.Org.Chem.2023,43,265273 2023 Shanghai Institute of Organic Che
3、mistry,Chinese Academy of Sciences http:/sioc- DOI:10.6023/cjoc202205038 研究论文研究论文 配体调控钯催化乙烯基环状碳酰胺和异氰酸酯的差异性转化 熊 威a 石 斌a 姜 烜a 陆良秋*,a,b 肖文精a(a华中师范大学化学学院 武汉 430079)(b河南师范大学化学化工学院 河南新乡 453007)摘要摘要 用配体调控策略,通过钯催化发展了乙烯基环状碳酰胺和异氰酸酯之间的两类差异性转化,选择性地合成了多取代的共轭二烯脲类化合物和四氢嘧啶酮衍生物.当反应以 Pd2(dba)3CHCl3(dba:dibenzylidenea
4、cetone)为催化剂前体、以单齿配位的 N,N-二甲基亚磷酰胺(MonoPhos)为配体时,可以高选择性地得到一系列线性的共轭二烯脲类衍生物;将配体改为双齿配位的 1,3-双(二苯基膦)丙烷(DPPP)时,利用相同的原料则能够合成一系列环状的四氢嘧啶酮类化合物.这一研究通过简便的配体调控策略,为含氮化合物的多样性合成提供了新方法.关键词关键词 配体调控;钯催化;脲;烯基碳酰胺;异氰酸酯 Ligand-Switched Pd-Catalyzed Divergent Transformations of Vinyl Cyclic Carbamates and Isocyanates Xiong,
5、Weia Shi,Bina Jiang,Xuana Lu,Liangqiu*,a,b Xiao,Wenjinga (a College of Chemistry,Central China Normal University,Wuhan 430079)(b School of Chemistry and Chemical Engineering,Henan Normal University,Xinxiang,Henan 453007)Abstract Synthesis of urea compounds is highly significant for pharmaceutical ch
6、emistry,agricultural chemistry,matterials science and organic synthesis.By ultilizing ligands to switch the chemoselectivity,two transformations of vinyl cyclic carbamates and isocyanates were developed to afford linear and cyclic ureas in a controlled manner.When phosphoramidite was used as the mon
7、odentate P-ligand,a wide range of(E)-1,3-diene-substituted linear ureas were produced in high yields and selectivity(21 examples,51%95%yields).While,using bidentate biphosphine ligand to replace the phosphoramidite ligand,a variety of highly functionalized vinyl-substitued cyclic ureas,tetrahydro-2-
8、pyrimidinones,were delivered instead starting from the same chemical feedstocks(8 examples,72%94%yields).To illusrate the switched chemoselectivity,two possible reaction mechanisms were proposed based on the experiment results and proceeding literatures.The keys of these two reactions,dienylation an
9、d annulation,are the-hydride elimination and the N-allylic alkylation of ally-Pd species,respectively.It is supposed that the basicity of the ligand will affect the reactivity of-ally-Pd intermediates toward electrophilic ring closing.It is believed that this research not only enriches the applicati
10、on of vinyl carbamate reagents in organic synthesis,but also provides a new protocol to access significant nitrogen-containing molecules.Keywords ligand-switched;palladium catalysis;urea;vinyl carbamate;isocyanate 1 Introduction Vinyl carbamates are a kind of versatile building blocks that are widel
11、y utilized as precursors for Pd-catalyzed an-nulation reactions.1 In 2000,Hollinshead et al.2 reported a(51)annulation of 5-vinyloxazolidin-2-ones with CO.In 2006,Tunge et al.3 exploited 6-vinyl oxazinanone rea-gents for Pd-catalyzed asymmetric(42)dipolar annula-tions with benzylidene lononitriles.I
12、n 2013,Ooi et al.4 accomplished a highly enantio-and diastereoselective(32)annulation of 5-vinyloxazolidinones and electro-defi-cient trisubstituted alkenes.In the recent decade,vinyl carbamate reagents have been widely applied for azahet-erocycle synthesis through Pd-catalyzed annulations,5 while,t
13、here were only a few examples on their application in the synthesis of poly-substituted butadienes.6 To con-tinue our research studies on transition metal catalyzed 有机化学 研究论文 266 http:/sioc- Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences Chin.J.Org.Chem.2023,43,265273 dipolar cy
14、cloadditions,7 herein,we accomplished two kinds of chemoselective transformations of vinyl cyclic carbamates and isocyanates,which were controlled by ligands and afforded linear dienyl and cyclic ureas in good selectivity.In 2003,Alper et al.8 reported a Pd-catalyzed ring-expansion reaction of 2-vin
15、ylpyrrolidines with aryl isocy-anates9 to form seven-membered cyclic ureas.During the study of ligand effect,they found that PPh3 gave the varied mixture of diene-substituted linear ureas and cyclic ureas which were heavily relied on the electronic characteristics of isocyanates(Scheme 1a).In 2020,w
16、e disclosed a Pd-catalyzed enantioselective(82)annulation of vinyl car-bamates with photogenerated ketenes,affording chiral 10-membered cyclic carbamates with the CO2 unit remained(Scheme 1a).10 As a continuation of this work,we planned to develop a similar annulation reaction between the same vinyl carbamates and isocyanates.Out of our expectation,we disclosed two ligand-switched decarboxy-lative dienylation and(42)annulation(Scheme 1c).Dif-ferent from Alpers work,the chemoselectivity of both r
