A gas chromatographic investigation of the volatile part of a pineapple concentrate led to the identification of 59 substances, 35 of which were not previously found in pineapple. The identifications and syntheses of some esters (Δ3- and Δ4-unsaturated, β-hydroxy, β-acetoxy, and δ-acetoxy) and of a new sulfur compound are given.
Formation of unsaturated esters in the single electron transfer reaction of cyclopropanone acetals with quinones under non-irradiated conditions
作者:Manabu Abe、Akira Oku
DOI:10.1016/s0040-4039(00)73235-7
日期:1994.5
Unsaturated esters were formed from cyclopropanone acetals in the reaction with DDQ or chloranil, where ring-opened CC and CO bonded adducts were the intermediates formed via a SET mechanism resulting in the ester formation.
Synthesis of Allylboranes via Cu(I)-Catalyzed B–H Insertion of Vinyldiazoacetates into Phosphine–Borane Adducts
作者:Denis Drikermann、Robert S. Mößel、Walid K. Al-Jammal、Ivan Vilotijevic
DOI:10.1021/acs.orglett.9b04619
日期:2020.2.7
Cu(I) catalysts enable C-B bond formation via direct insertion of vinyldiazoacetates into B-H bonds of borane-phosphine Lewis adducts to form phosphine-protected allylboranes under mild conditions. The resulting allylborane-phosphine Lewis adducts can be used in the diastereoselective allylation of aldehydes directly without the need for removal of the phosphine. The allylation reaction proceeds with
Vinyldiazo compounds undergo a thermal electrocyclization to form pyrazoles in yields of up to 95%. The reactions are operationally simple, use readily available starting materials, require no intervention of a catalyst, and enable the synthesis of mono-, di- and tri-substituted pyrazoles. With the ability to produce highly substituted pyrazoles and the flexibility in installing various types of substituents
Formaldehydedimethyl dithioaoetal S,S-dioxide () reacted uith an alkyl bromide or a 2-alkenyl bromide () under phase-transfer sonditions using 50% aq. NaOH to give an alkyl or 2-alkenyl derivative of , whereas, in the reaction with in the presence of Kg2CO3KI in HMPA, formed a 1-alken-3-yl derivative. Transformation of these products into the corresponding carboxylio esters uae also described.
甲醛二甲基二硫代缩醛S,S-二氧化物()在烷基转移或2-烯基溴()的作用下,使用50%HCl水溶液进行反应。NaOH生成的烷基或2-烯基衍生物,而在HMPA中与Kg 2 CO 3 KI存在下反应,形成1-烯-3-基衍生物。还描述了将这些产物转化成相应的羧基酯。