6963-10-6Relevant academic research and scientific papers
Application of sulfuryl chloride for the quick construction of β-chlorotetrahydrofuran derivatives from homoallylic alcohols under mild conditions
Zeng, Xianghua,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
, p. 2391 - 2396 (2013/09/23)
An efficient and mild method is reported for the construction of β-chlorotetrahydrofuran derivatives by 5-endo chlorocycloetherification of homoallylic alcohols. The system employs sulfuryl chloride as the chlorinating agent under catalyst-free conditions. A variety of homoallylic alcohols with aryl or alkyl substituents were smoothly converted into β- chlorotetrahydrofurans in yields up to 98%.
THE STERIC COURSE OF THE REACTIONS OF 2,3-DIHALOTETRAHYDROPYRANS WITH GRIGNARD REAGENTS
Berti, Giancarlo,Catelani, Giorgio,Monti, Luigi,Ventresca, Giovanni
, p. 3973 - 3980 (2007/10/02)
The steric course of some reactions of 2,3-dihalotetrahydropyrans with sodium methoxide and with methyl- and phenyl-magnesium bromides has been reinvestigated.Whereas the methanolysis of the cis- and trans-dichlorides occurs with practically complete inversion, it has been confirmed that their reactions, as well as those of dibromides, with methylmagnesium bromide are non-stereospecific, yielding mixtures of trans- and cis-3-halo-2-methyl-tetrahydropyrans in ratios that are independent of the configurations of the starting dihalides.It has been further established that grignard reagents cause equlibration of cis- and trans-dihalide mixtures in a reaction that is much faster than the Grignard coupling step.
β-Halogeno Ether Synthesis of Olefinic Alcohols: Stereochemistry and Conformation of 2-Substituted 3-Halogenotetrahydro-pyran and furan Precursors
Crombie, Leslie,Wyvill, Robert D.
, p. 1971 - 1982 (2007/10/02)
Ring-scission of cis- or trans-2-alkyl- (or aryl-) 3-chlorotetrahydropyrans proceeds regioselectively and highly stereoselectively to give (E)-alk-4-en-1-ols, but in the parallel tetrahydrofuran series (Z)-/(E)-mixtures, dependent on percursor geometry, are formed.In this paper the stereochemistry and conformation of the tetrahydro-pyran and - furan precursors are considered.The cis/trans-composition of 2,3-dihalogenotetrahydro-pyrans and-furans made by various routes is reported.Reaction with Grignard reagents gives separable cis-/trans-mixtures the stereoisomeric composition of which, in the cases examined, does not depend on the stereoisomeric composition of the dihalide, but does vary with the halogen and the composition of the Grignard or dialkylmagnesium; possible reasons are discussed.The stereochemistry and conformation of the 2-alkyl- (or aryl-)3-chlorotetrahydropyrans is analysed by n.m.r. methods (J2a,3acis ca. 1.5 Hz; J2a,3atrans ca. 9.8 Hz) but assignments for the two tetrahydrofuran series with J2,3 2.6-3.6 and 4.3-5.9 are made uncertain by pseudorotation.The stereochemical identity of the two series is rigorously proved by isolation of cis- and trans-2-allyl-3-chlorotetrahydrofuran.On the one hand the former is hydrogenated to the cis-2-propyl compound, correlated with other members of the alkyl series, but on the other it is oxidised and the acid is converted into the cis-p-bromophenyl ester.The stereochemistry and conformation of the latter is rigorously demonstrated by an X-ray structure.The stereochemistries and conformations of the 2-deuterio- and 2-methoxy-3-chlorotetrahydropyrans are discussed, and consideration is then extended to the 2-alkyl-3-chloro-2-methyltetrahydro-pyran and -furan series.
