A new easy method for the synthesis of cyclic halogenoethers and halogenolactones
作者:Morris Srebnik、Raphael Mechoulam
DOI:10.1039/c39840001070
日期:——
Oxidation of halogen salts with m-chloroperbenzoic acid in the presence of 18-crown-6 and of suitable hydroxy or carboxy alkenes leads readily to high yield production of cyclichalogenoethers of halogenolactones.
Halocyclization of Unsaturated Alcohols and Carboxylic Acids Using Bis(<i>sym</i>-collidine)iodine(I) Perchlorate
作者:Robert D. Evans、Joseph W. Magee、J. Herman Schauble
DOI:10.1055/s-1988-27731
日期:——
Reaction of I(collidine)+ 2 ClO- 4 with unsaturated alcohols and carboxylic acids in dichloromethane at ambient temperature has afforded three- to seven-membered-ring iodoethers and four- to seven-membered-ring iodolactones, respectively, in moderate yields and generally with high regioselectivity. The reaction is of particular utility for synthesis of 2-(1-iodoalkyl)oxiranes and -oxetanes.
Treatment of homoallylic alcohols with NaIO4/NaHSO3 reagent in aqueous t-BuOH under mild conditions produced tetrahydrofuran derivatives together with iodohydrins in a stereospecific manner. The reaction pathways of the formation of tetrahydrofurans from trans- and cis-homoallylic alcohols were found to be different. The present method provides a new approach to various alkylated tetrahydrofuran derivatives
A facile and efficient one-pot synthesis of thiochromans from bis(2-formylphenyl) disulfide and alkenols via iodine-promoted generation and subsequent intramolecular cycloaddition of ortho-thiobenzoquinone methides
Stereoselective synthesis of tetrahydrofuro- and tetrahydropyrano[3,2-c]benzothiopyrans was achieved by intramolecular [4+2]cycloaddition of o-thiobenzoquinone methides that were generated in situ from bis(2-formylphenyl) disulfide and alkenols in the presence of iodine under mild reaction conditions.
立体选择性合成四氢呋喃-和四氢吡喃并[3,2- c ]苯并硫代吡喃,是通过在碘存在下由双(2-甲酰基苯基)二硫化物和烯醇原位生成的邻-硫代苯醌甲基化物的分子内[4 + 2]环加成反应而实现的。在温和的反应条件下。
Enantioselective Mercuriocyclization of γ-Hydroxy-<i>cis</i>-alkenes
作者:Sung Ho Kang、Mihyong Kim
DOI:10.1021/ja029777d
日期:2003.4.1
Asymmetric mercuriocyclization of gamma-hydroxy-(Z)-alkenes has been achieved using Hg(II) complexed with tartrate-derived 4-(2-naphthyl)bisoxazoline as chiral ligand to give rise to 2-monosubstituted tetrahydrofurans in 86-95% ee. Not only the linker connecting two oxazolines but also their 4-substituents were found crucial for high enantioselectivity. In addition, tuning the ketal protecting group of tartrate as well as adding MeOH and K(2)CO(3) worked beneficially.