Gas phase thermalisomerizations of twelve acetylenic systems, all of which can in principle undergo two successive pericyclic steps, are described. The substrates, the syntheses and spectroscopic properties of which are presented, are formal derivatives of but-2-yne, with different functional groups in the 1- and the 4-positions. The Cope, Claisen, Claisen ester, retro-ene, 1,5-hydrogen shift, and
Synthese et configuration absolue d'α-cyclopropylcetones aliphatiques optiquement actives
作者:J.F. Tocanne、R.G. Bergmann
DOI:10.1016/0040-4020(72)80145-5
日期:1972.1
Synthesis, optical purities and absolute configurations of some aliphatic α-cyclopropylketones or 2-alkyl 1-cyclopropyl (methyl) ketones (in which alkyl groups are methyl or ethyl or a polymethylenic chain) are described.
Solvolysis of acyclic allenic tosylates shows that the allene group participates strongly to give cyclopropyl ketones and methylenecyclobutanols. Whenever C4 and C5 of the 3-methyl penta-1,2 dien-5-yl system carry different substituents, an apparent exchange of position between them occurs during the cyclisation.
Cyclopropane Compatibility with Oxidative Carbocation Formation: Total Synthesis of Clavosolide A
作者:GuangRong Peh、Paul E. Floreancig
DOI:10.1021/ol302744t
日期:2012.11.2
Cyclopropane-substituted allylic ethers react with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to form oxocarbenium ions with no competitive ring cleavage. This reaction can be used for the preparation of cyclopropane-substituted tetrahydropyrans. The protocol was used as a key step in the total synthesis of the sponge-derived macrolide clavosolide A.