Experimental and calculated activation parameters for ring opening of the 1-bicyclo[1.1.1]pentyl radical: the effect of bridgehead substituents
摘要:
Ring opening of the 1-bicyclo[1.1.1]pentyl, 3-pentyl-1-bicyclo[1.1.1]pentyl, and 3-carbomethoxy-1-bicyclo[1.1.1]pentyl radicals has been studied by experiment and by molecular orbital theory. Our results indicate that the parent system 1a is extremely reluctant to ring open, with an energy barrier of at least 26 kcal mol-1. The ester- and phenyl-substituted radicals rearrange somewhat more readily, with barriers of about 25 and 21 kcal mol-1, respectively. This trend is also observed in the molecular orbital treatment of these processes. Previous reports that include radical rearrangements of this type must now be reconsidered in light of our new data.
Synthesis of 1,3-Substituted Cyclobutanes by Allenoate-Alkene [2 + 2] Cycloaddition
作者:Michael L. Conner、M. Kevin Brown
DOI:10.1021/acs.joc.6b01446
日期:2016.9.2
A method for the [2 + 2] cycloaddition of terminal alkenes with allenoates is presented. This process allows for the rapid synthesis of 1,3-substituted cyclobutanes in high yield under simple and robust reaction conditions.
Wacker Oxidation of Methylenecyclobutanes: Scope and Selectivity in an Unusual Setting
作者:Jan Sietmann、Marius Tenberge、Johannes M. Wahl
DOI:10.1002/anie.202215381
日期:2023.2.6
Methylenecyclobutanes undergo Wacker oxidation towards cyclopentanones under mild reaction conditions. A semi-pinacol-type rearrangement is proposed to be responsible for the intermediary 1,2-shift, which not only explains the formation of the products, but also rationalizes the reaction outcomes in terms of site-, regio- and enantioselectivity.
1‐Azaspiro[3.3]heptane as a Bioisostere of Piperidine**
作者:Alexander A. Kirichok、Hennadii Tkachuk、Yevhenii Kozyriev、Oleh Shablykin、Oleksandr Datsenko、Dmitry Granat、Tetyana Yegorova、Yuliya P. Bas、Vitalii Semirenko、Iryna Pishel、Vladimir Kubyshkin、Dmytro Lesyk、Oleksii Klymenko‐Ulianov、Pavel K. Mykhailiuk
DOI:10.1002/anie.202311583
日期:2023.12.18
1-Azaspiro[3.3]heptanes were synthesized, characterized, and validated biologically as bioisosteres of piperidine. Incorporation of this core into the anesthetic drug bupivacaine instead of the piperidine ring resulted in a patent-free analogue with high activity.
3-Substituted-1-(Trimethylsilylmethyl)cyclobutyl Cations: Stereochemistry of Solvent Capture of β-Trimethylsilyl Carbocations
作者:Xavier Creary
DOI:10.1021/acs.joc.2c02387
日期:2023.2.17
carbocationic intermediates formed from loss of trifluoroacetate ion. These cationic intermediates react to give a significant amount of methylethersubstitution products along with the expected alkene elimination products. Different methylethersubstitution products are formed from isomeric trifluoroacetates, and complete retention of configuration of the ether group relative to the starting trifluoroacetates
Spiro[3.3]heptane as a Saturated Benzene Bioisostere**
作者:Kateryna Prysiazhniuk、Oleksandr P. Datsenko、Oleksandr Polishchuk、Stanislav Shulha、Oleh Shablykin、Yelyzaveta Nikandrova、Kateryna Horbatok、Iryna Bodenchuk、Petro Borysko、Dmytro Shepilov、Iryna Pishel、Vladimir Kubyshkin、Pavel K. Mykhailiuk
DOI:10.1002/anie.202316557
日期:2024.2.26
The spiro[3.3]heptane core, with the non-coplanar exit vectors, was shown to be a saturated benzene bioisostere. This scaffold was incorporated into the anticancer drug sonidegib (instead of the meta-benzene), the anticancer drug vorinostat (instead of the phenyl ring), and the anesthetic drug benzocaine (instead of the para-benzene). The patent-free saturated analogs obtained showed a high potency