89036-08-8Relevant articles and documents
A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones
Hosono, Kazumi,Kodama, Shintaro,Nomoto, Akihiro,Ochi, Takanori,Ogawa, Akiya,Tabuchi, Akihiro,Yamamoto, Yuki,Yamazaki, Kento
supporting information, p. 2906 - 2914 (2022/01/12)
A simple and efficient method for α-brominating lactones that affords α-bromolactones under mild conditions using tetraalkylammonium hydroxide (R4N) as a base was developed. Lactones are ring-opened with Br2 and a substoichiometric amount of PBr3, leading to good yields of the corresponding α-bromocarboxylic acids. Subsequent intramolecular cyclization over 1 h using a two-phase system (H2O/CHCl3) containing R4N afforded α-bromo lactones in good yields. This method can be applied at the 10 mmol scale using simple operations. α-Bromo-δ-valerolactone, which is extremely reactive and difficult to isolate, could be isolated and stored in a freezer for about one week using the developed method. Optimizing the solvent for environmentally friendly large-scale syntheses revealed that methyl ethyl ketone (MEK) was as effective. In addition, in situ-generated α-bromo-δ-valerolactone was directly converted into a sulfur-substituted functional lactone without difficulty by reacting it with a sulfur nucleophile in one pot without isolation. This new bromination system is expected to facilitate the industrial use of α-bromolactones as important intermediates.
Cine substitution in 2-oxabicyclo[4.2.0]octanones and subsequent unusual rearrangements
Hassner, Alfred,Naidorf-Meir, Simha,Frimer, Aryeh A.
, p. 4051 - 4058 (2007/10/03)
Reaction of 2-chlorooxabicyclo[4.2.0]octanone 5 with several nucleophiles was examined and found to differ significantly from those of carbon analog 1. MeO- and PhS- led either to products of cine substitution 9 or of ring opening to cyclobutenones 8. With most enolates cine substitution occured via C-alkylation of the intermediate oxidoallyl cation in spite of formation of a new C-C bond between two quaternary carbons; with nitroalkanes O-alkylation was preferred. With azide as a nucleophile, further transformations occurred, among them an oxy-promoted electrocyclic cyclobutane opening, with incorporation of a phenyl triazole unit and final formation of the unusual product 19a. Evidence for a mechanism explaining formation of 19a was obtained by isolation of intermediates. Thermolysis or photolysis of 8e or 9b led via electrocyclic ring opening to a vinyl ketene which was trapped by MeOH, alkenes, dienes, or oxygen to produce polyfunctional unsaturated esters 29 and 30 or 8-membered ring lactone 31, fused cyclobutanones 33 and 34, pyranone 38, or γ-lactone 39, respectively.
An Useful Synthetic Method for 3-Substituted δ-Lactones. Synthesis of (+/-)-Secocrispiolide
Kato, Michiharu,Ouchi, Akihiko,Yoshikoshi, Akira
, p. 1479 - 1486 (2007/10/02)
2-Phenylthio-2-penten-5-olide (1) acted as a reactive Michael acceptor toward some typical carbon nucleophiles to give 3-substituted 2-phenylthio-5-pentanolides (2) which were convertible both to 3-substituted 5-pentanolides by reductive desulfurization and to 3-substituted 2-penten-5-olides by sulfenic acid syn elimination of the sulfoxides 4 derived from 2.The Pummerer rearrangement of 4 provided 3-substituted 2-phenylthio-2-penten-5-olides and/or 2-hydroxy-2-penten-5-olides. (+/-)-Secocrispiolide was synthesized via the adduct obtained by the Michael reaction of 1 with the Grignard reagent prepared from 2,6-dimethylbenzyl bromide and magnesium.
UNUSUAL TRANSFORMATIONS IN OXABICYCLOOCTANONES. AN APPARENT OXY-PROMOTED ELCTROCYCLIC OPENING INVOLVING FUSED CYCLOBUTANOLS
Hassner, Alfred,Naidorf-Meir, Simha,Gottlieb, Hugo E.,Frolow, Felix
, p. 5669 - 5672 (2007/10/02)
Reaction of oxabicyclooctanone 3 with nucleophiles involves not only cine substitution but ring opening to cyclobutenones which are capable of further transformations.With azide as a nucleophile, further reactions occur, among them an oxy-promoted electrocyclic cyclobutane opening, with final formation of 8, the structure of which was verified by X-ray diffraction.
2-(PHENYLTHIO)-2-PENTEN-5-OLIDE, A NEW BUILDING BLOCK FOR THE SYNTHESIS OF 3-SUBSTITUTED γ-LACTONES
Kato, Michiharu,Ouchi, Akihiko,Yoshikoshi, Akira
, p. 1511 - 1514 (2007/10/02)
2-(Phenylthio)-2-penten-5-olide, readily accessible from γ-valerolactone, showed high electrophilic reactivities toward some typical carbon nucleophiles to give 3-substituted 2-(phenylthio)pentanolides, which were convertible to a variety of 3-substituted
