Synthesis of Spiro[4.5]trienones by Intramolecular ipso-Halocyclization of 4-(p-Methoxyaryl)-1-alkynes
摘要:
A wide variety of 3-halospiro[4.5]trienones are readily prepared in good to excellent yields by the intramolecular ipso-halocyclization of 4-(p-methoxyaryl)-1-alkynes under mild reaction conditions. ICl, I2, and Br2 are all effective electrophiles for this process under carefully optimized reaction conditions.
Electronic effect on the regioselectivity in the ring opening of para-substituted phenyloxiranes by acetylides
作者:Mitsuru Shindo、Tomoyuki Sugioka、Kozo Shishido
DOI:10.1016/j.tetlet.2004.10.049
日期:2004.12
The electronic effect on the regioselectivity in the alkynylation of phenyloxiranes was investigated using three kinds of metal acetylides. BF3 mediated lithium acetylide provided either the alpha- or beta-alkynylated products by controlling the effect of the para-substituents of the phenyloxiranes. LiClO4 mediated lithium acetylide and titanium acetylide, on the other hand, afforded predominantly the beta- and alpha-products, respectively. (C) 2004 Elsevier Ltd. All rights reserved.