Stereochemical studies. X. Synthesis of some epimeric δ-lactones
作者:Ellen Cooke、Themistocles C. Paradellis、John T. Edward
DOI:10.1139/v82-006
日期:1982.1.1
Stereospecific syntheses are reported for the δ-lactones 3, 5, 8, 17, and 26.
报道了δ-内酯3、5、8、17和26的立体特异性合成。
Stereochemistry of the reaction of Si–phenyl silenes with butadienes: elaboration of the silacycloadducts to provide a novel route to substituted lactones
作者:Mahesh J. Sanganee、Patrick G. Steel、Daniel K. Whelligan
DOI:10.1039/b404175e
日期:——
silacycles accompanied by variable amounts of competing ene, [2 + 2] and silene dimer by-products. The silacycles are formed with good chemo- and stereo-selectivity and provide access to diols and lactones via a phenyl-triggered Fleming-Tamao oxidation.
A method for the chromatographic resolution of tetrahydropyran-2-ones
作者:Philip Ashworth、Shiddappa L. Belagali、Sharon Casson、Anna Marczak、Philip Kocieński
DOI:10.1016/s0040-4020(01)80729-8
日期:1991.12
The spirocyclic ortholactones prepared from certain tetrahydropyran-2-ones (valerolactones) and (1R)-1-phenylpropan-1,3-diol are readily separable by flash chromatography on silica gel. Hydrolysis of the resolved ortholactones then provides the pure homochiral lactones.
Exploiting the vicinal disubstituent effect on the diastereoselective synthesis of γ and δ lactones
作者:Elisabetta Brenna、Francesco Dalla Santa、Francesco G. Gatti、Giuseppe Gatti、Davide Tessaro
DOI:10.1039/c8ob02715c
日期:——
diastereoisomer ring closes substantially more rapidly than the syn isomer ring; (ii) the anti-vic effect is much stronger than the classical Thorpe–Ingold effect (known also as the gem-disubstituent effect), instead the syn diastereoisomers have rate constants comparable to that of the gem-disubstituted ester; (iii) the vic-effect can be enhanced by increasing the steric hindrance of one of the two substituents
The reaction of 4,5-epoxy-2-hexenoate (3) with methylcopper, dimethylcuprate, and their BF3, complexes gave predominantly the γ-methylated product (5) via SN2 process, while the reaction with methylcyanocuprate, higher order dimethylcyanocuprate and their BF3 complexes afforded preferentially the α-methylated product (4) via SN2 ' process. Anti-diastereoselectivity was observed regardless of the substitution
4,5-环氧-2-己烯酸酯(3)与甲基铜,二甲基铜酸酯及其BF 3配合物的反应主要通过S N 2过程得到的γ-甲基化产物(5),而与甲基氰脲酸酯的反应则更高级通过S N 2'方法,优先得到二甲基氰基丙二酸酯及其BF 3络合物,得到α-甲基化产物(4)。无论取代模式如何,均观察到抗非对映选择性。BF 3 ·OEt 2的存在降低了抗选择性,在某些情况下,在BF 3 ·OEt过量的情况下观察到相反的同-非对映选择性2。在CNDO / 2计算的基础上讨论了这些区域选择性和立体选择性。