Comparison of syn dehydrohalogenations from -1-bromo-2-chlorocycloalkanes promoted by complex base and by potassium -butoxide
作者:Alan P. Croft、Richard A. Bartsch
DOI:10.1016/s0040-4039(00)88009-0
日期:1983.1
Compared with t-BuOK-t-BuOH, syn eliminations from trans-1-bromo-2-chlorocycloalkanes (C4-C8) induced by NaNH2-NaO-t-Bu in THF are rapid, exhibit greater propensity for dehydrechlorination and show little sensitivity to ring size of the dihalocycloalkane.
The pseudohelical hydrocarbons (R)-6, (S)-7, and (R)-8 and the helical hydrocarbon (P)-9, formally derived from the helical hydrocarbon (P)-4 by stepwise replacement of each of the four-membered rings by a five-membered ring, have been prepared. Their optical rotations vary systematically, both in magnitude and sign. Of the extremes, (P)-4 represents the usual case of a right-handed dextrorotatory
A Modular Access to 1,2‐ and 1,3‐Disubstituted Cyclobutylboronic Esters by Consecutive Radical Additions
作者:Jean Michalland、Nicolas Casaretto、Samir Z. Zard
DOI:10.1002/anie.202113333
日期:2022.1.17
Using the strain inherent in a cyclobutyl ring to counteract the stabilization of a radical adjacent to a boronic ester allows the synthesis a broad variety of 1,2- and 1,3-disubstituted cyclobutylboronic esters.
Cyclobutylidenes from geminal dihalogenocyclobutanes
作者:Udo H. Brinker、Gilbert Schenker
DOI:10.1039/c39820000679
日期:——
Cyclobutylidene, or a related carbenoid, can be generated by reaction of geminal dibromocyclobutane with methyl-lithium at temperatures as low as –78 °C to yield methylanecyclopropane and cyclobutene nearly quantitatively.
Asymmetric Synthesis and Translational Competence of <scp>l</scp>-α-(1-Cyclobutenyl)glycine
作者:Lasanthi P. Jayathilaka、Mahua Deb、Robert F. Standaert
DOI:10.1021/ol049026b
日期:2004.10.1
[reaction: see text] L-alpha-(1-Cyclobutenyl)glycine (1-Cbg) was targeted as a potentially translatable analogue of isoleucine and valine and as a useful building block for peptides. An enantioselective synthesis was executed in which the key step was diastereoselective addition of 1-cyclobutenylmagnesium bromide to the sulfinimine 2b derivedfrom (S)-t-butanesulfinimide and tert-butyl glyoxylate.