Intramolecular cycloaddition reactions of ketenes and keteniminium salts with alkenes

Abstract

Contents I. Introduction 793 A. Ketene Generation 793 B. Tether Length 794 C. Effect of Substituents on the Alkene 794 D. Reaction Conditions 794 II, Substituents on the Ketene 794 A. Aldoketenes 795 1. Thermal Cycloadditions 795 2. Photochemical Addition of Aldoketenes 795 to the Double Bonds of u./S-Unsaturated Carbonyl Compounds B. Ketoketenes 796 C. a,/i-Unsaturated Ketenes 796 1. Type III Cycloadditions of 797 «,/3-Unsaturated Ketenes 2. Type II Cycloadditions of 799 a,d-Unsaturated Ketenes 3. Type I Cycloadditions of 801 a\ij-Unsaturated Ketenes D. Cyclopropylketenes 802 E. Arylketenes 802 F. Chloroketenes 803 G. Alkoxyketenes 803 FI. cr-Ketoketenes 804 I. Sulfonylketenes 805 J. Iminoketenes 805 K. Miscellaneous Ketenes 805 L. Cycloaddition of Ketenes to Carbonyl 806 Compounds III. Keteniminium Salts 806 A. Aldoand Ketoketiniminium Salts 806 B. Alkoxyketeniminium Salts 807 IV. Cycloreversion of Polycyclic Cyclobutanones 808 V. Conclusion 808 VI. Addendum 808 VII. References and Notes 810

Multiphase telomerisation of butadiene with acetic acid and acetic anhydride

“…the dimerisation or the cycloaddition to conjugated dienes [22,23]. Vinyl cyclobutanone, which is formed by the addition of ketene and butadiene, could not be detected in this case.…”

Cycloaddition and Electrocyclic Reactions of Vinylketenes, Allenylketenes, and Alkynylketenes

“…Ketene cycloadditions have been extensively reviewed 1,3,4,7,29,30,32 and will not be considered in detail in this chapter. Ketene [2+2] cycloadditions, including those of vinylketenes, are generally agreed to involve an initial orthogonal arrangement of the two reactants, with the smaller ketene substituent (R S ) closest to the alkene (Scheme 11).…”

“…[4][5][6][7] The reactivity of vinylketenes is attenuated by the presence of bulky groups and silyl substituents. The presence of a conjugated double bond in vinylketenes and allenylketenes, and a conjugated triple bond in alkynylketenes, allows a variety of additional cycloaddition pathways that are unavailable to simpler ketenes.…”

Recent Progress in the Chemistry of Keteniminium Salts

“…但研究表明, 烯酮亚胺盐的稳定性并不 像想象中那么差. 如烯酮亚胺盐在与烯烃的环加成反应 中表现得比烯酮更稳定, 自身不易聚合、反应选择性更 高 [8] . 近年来, 围绕这种具有高亲电性且有一定稳定性 的氮杂联烯的反应研究逐渐增多.…”