63298-04-4Relevant academic research and scientific papers
A new strategy for efficient synthesis of medium and large ring lactones without high dilution or slow addition
Zhao, Wanxiang,Li, Zigang,Sun, Jianwei
supporting information, p. 4680 - 4683 (2013/05/09)
We have developed an efficient method for medium and large ring lactone synthesis by a conceptually different ring-expansion strategy. The design of an unprecedented ring conjunction mode of oxetene, combined with the appropriate choice of a Lewis acid promoter and an additive, constitutes the key components of the new process. Enabled by this new approach, the reaction does not require high dilution or slow addition.
SUBSTITUTION REACTIONS OF 2-BENZENESULPHONYL CYCLIC ETHERS WITH CARBON NUCLEOPHILES
Brown, Dearg S.,Bruno, Maurizio,Davenport, Raymond J.,Ley, Steven V.
, p. 4293 - 4308 (2007/10/02)
Direct substitution of 2-benzenesulphonylcyclic ethers was studied using a variety of carbon nucleophiles.These nucleophiles included organozinc reagents (derived from aryl, vinyl and alkynyl Grignard reagents) or silyl enol ethers, silyl ketene acetals,
d1- and d3-Selective Reactions of Sulfur-substituted Allylic Titanium Derivatives with Aldehydes and Ketones
Widler, Leo,Weber, Theodor,Seebach, Dieter
, p. 1329 - 1344 (2007/10/02)
As previously reported, double deprotonation of allylmercaptane with butyllithium produces the moderately to poorly d3-selective dilithium derivative 1a of thioacrolein (or 1-thiabutadiene).Addition of an equimolar amount of chlorotriisopropoxytitanium generates a reagent 1c, which combines with aldehydes and ketones almost exclusively in the γ-position (d3-reactivity, products 2, Table 1, 18 examples).The 2-methyl analogue 4b exhibits a similar d3-selectivity, with somewhat lower chemical yields (products 5, Table 2, 7 examples).In contrast to the dianion deri vatives, methyl- and phenyl-allyllithium combine with chlorotriisopropoxytitanium to give reagents (6a, 6b) which add to the same electrophiles practically only in the α-RS-position (d1-reactivity, products 7 and 8, Table 3, 12 examples).Possible conversions of the selectively produced α- and γ-adducts to vinyloxiranes, to γ-hydroxy- and to ε-keto aldehyde derivatives are discussed (Scheme 1).Some examples of Hg(II)-assisted alcoholyses (CH3OH, C2H5OH) of γ-adducts 2 to 2-alkoxytetrahydrofurans (9, 10) are described (Scheme 2, Table 4). "Titanation" of the Li derivatives not only causes high regioselectivity, but also excellent chemical selectivity of the nucleophilic reagents: they preferentially add to aldehydes vs. ketones and are compatible with other functional groups, such as CN, NO2, I, in the substrate.
