1483-09-6Relevant academic research and scientific papers
Regioselective Carbonylation of 2,2-Disubstituted Epoxides: An Alternative Route to Ketone-Based Aldol Products
Hubbell, Aran K.,Lapointe, Anne M.,Lamb, Jessica R.,Coates, Geoffrey W.
, p. 2474 - 2480 (2019)
We report the regioselective carbonylation of 2,2-disubstituted epoxides to β,β-disubstituted β-lactones. Mechanistic studies revealed epoxide ring-opening as the turnover limiting step, an insight that facilitated the development of improved reaction conditions using weakly donating, ethereal solvents. A wide range of epoxides can be carbonylated to β-lactones, which are subsequently ring-opened to produce ketone-based aldol adducts, providing an alternative to the Mukaiyama aldol reaction. Enantiopure epoxides were demonstrated to undergo the carbonylation/ring-opening process with retention of stereochemistry to form enantiopure β-hydroxy esters.
SYSTEMS AND METHODS FOR REGIOSELECTIVE CARBONYLATION OF 2,2-DISUBSTITUTED EPOXIDES
-
Paragraph 0087; 0170; 0177, (2020/06/05)
Provided are methods of carbonylating cyclic substrates to produce carbonyl ated cyclic products. The cyclic substrates may be 2, 2-di substituted epoxides and the cyclic products may be β,β-di substituted lactones. The method may be carried out by forming and pressurizing a reaction mixture of the cyclic substrate, a solvent, carbon monoxide, and a [LA+][CO(CO)4-] catalyst, where [LA+] is a Lewis acid capable of coordinating to the cyclic substrate. The method may proceed with a regioselectivity of 90:10 or greater. The resulting carbonylated cyclic products may be converted to ketone aldol products that retain the stereochemistry and enantiomeric ratio of the carbonyl ated cyclic products.
Syntheses of β-lactones, 6: One-step synthesis of β-lactones by aldolization of ketones or aldehydes with 1-acylbenzotriazoles
Wedler, Christine,Kleiner, Katharina,Kunath, Annamarie,Schick, Hans
, p. 881 - 885 (2007/10/03)
Benzotriazolides 1 of alkanoic acids with one hydrogen atom in α-position to the carboxamide group can be deprotonated with lithium diisopropylamide or lithium hexamethyldisilazanide to amide enolates 2 which condense at -90 to -95°C with ketones or aldehydes 3 to afford benzotriazolides of O-lithiated β-hydroxylalkanoic acids 4. These reactive carboxamide derivatives cyclize with elimination of lithium benzotriazolide to the corresponding di- and trisubstituted β-lactones. With regard to the formation of β-monosubstituted β-lactones from aldehydes the use of benzotriazolides as active carboxylic acid derivatives proved to be superior to the application of the corresponding phenyl esters. An α-unsubstituted β-lactone 6 was obtained from 1-acetylbenzotriazole only with cyclohexanone. The other carbonyl compounds 3 did not provide the corresponding α-unsubstituted β-lactones 6. VCH Verlagsgesellschaft mbH, 1996.
A Practical and Efficient Method for the Synthesis of β-Lactones
Danheiser, Rick L.,Nowick, James S.
, p. 1176 - 1185 (2007/10/02)
This paper describes a convenient one-step preparation of β-lactames based on the addition of thiol ester enolates to carbonyl compounds.Under the proper conditions the resulting aldolates undergo spontaneous cyclization to produce β-lactones in good to excellent yield.The new β-lactone synthesis provides access to 2-oxetanones with a variety of substituents and substitution patterns.In general, thiol ester enolates combine with carbonyl compounds to form the less sterically crowded β-lactone diasteromers, and in some cases the reaction proceeds with excellent stereoselectivity.In conjunction with the stereospecific decarboxylation of β-lactones, this chemistry also provides a very attractive approach to the synthesis of substituted alkenes.
