62360-06-9Relevant academic research and scientific papers
α-Alkylidene-γ-butyrolactone Formation via Bi(OTf)3-Catalyzed, Dehydrative, Ring-Opening Cyclizations of Cyclopropyl Carbinols: Understanding Substituent Effects and Predicting E/Z Selectivity
Sandridge, Matthew J.,McLarney, Brett D.,Williams, Corey W.,France, Stefan
, p. 10883 - 10897 (2017/10/27)
A Bi(OTf)3-catalyzed ring-opening cyclization of (hetero)aryl cyclopropyl carbinols to form α-alkylidene-γ-butyrolactones (ABLs) is reported. This transformation represents different chemoselectivity from previous reports that demonstrated formation of (hetero)aryl-fused cyclohexa-1,3-dienes upon acid-promoted cyclopropyl carbinol ring opening. ABLs are obtained in up to 89% yield with a general preference for the E-isomers. Mechanistically, Bi(OTf)3 serves as a stable and easy to handle precursor to TfOH. TfOH then catalyzes the formation of cyclopropyl carbinyl cations, which undergo ring opening, intramolecular trapping by the neighboring ester group, subsequent hydrolysis, and loss of methanol resulting in the formation of the ABLs. The nature and relative positioning of the substituents on both the carbinol and the cyclopropane determine both chemo- and stereoselective outcomes. Carbinol substituents determine the extent of cyclopropyl carbinyl cation formation. The cyclopropane donor substituents determine the overall reaction chemoselectivity. Weakly stabilizing or electron-poor donor groups provide better yields of the ABL products. In contrast, copious amounts of competing products are observed with highly stabilizing cyclopropane donor substituents. Finally, a predictive model for E/Z selectivity was developed using DFT calculations.
Synthesis of Substituted Cyclopropanecarboxylates via Room Temperature Palladium-Catalyzed α-Arylation of Reformatsky Reagents
Greszler, Stephen N.,Halvorsen, Geoff T.,Voight, Eric A.
, p. 2490 - 2493 (2017/05/24)
The room temperature palladium-catalyzed cross-coupling of aromatic and heteroaromatic halides with Reformatsky reagents derived from 1-bromocyclopropanecarboxylates provides an exceptionally mild method for enolate α-arylation. The method is tolerant of a wide range of functionalities and dramatically shortens many of the existing routes to access widely used 1,1-disubstituted cyclopropanecarboxylate derivatives.
Preparative resolution of bromocyclopropylcarboxylic acids
Edwards, Andrew,Ryabchuk, Pavel,Barkov, Alexey,Rubina, Marina,Rubin, Michael
, p. 1537 - 1549 (2015/02/02)
A general and efficient method for the preparative resolution of α- and β-bromocyclopropylcarboxylic acids has been developed. This protocol involves a sequence of two crystallizations with pseudo-enantiomeric amines, cinchonine, and cinchonidine, which yield both enantiomers of the acid in highly enriched form. Both alkaloids can be easily recovered and reused multiple times without any loss of efficacy.
Highly stereoselective radical carbonylations of gem-dihalocyclopropane derivatives with CO
Nishii, Yoshinori,Nagano, Takao,Gotoh, Hideki,Nagase, Ryohei,Motoyoshiya, Jiro,Aoyama, Hiromu,Tanabe, Yoo
, p. 563 - 566 (2007/10/03)
A couple of radical carbonylations of gem-dihalocyclopropanes 1 using CO and Bu3SnH (formylation) or Bu3Sn(CH2CH=CH 2) (allylacylation) successfully proceeded to give trans and cis adducts (2 and 3) with good to
Bromine-magnesium exchange in gem-dibromocyclopropanes using Grignard reagents
Baird, Mark S,Nizovtsev, Alexey V,Bolesov, Ivan G
, p. 1581 - 1593 (2007/10/03)
Reaction of gem-dibromocyclopropanes with ethylmagnesium bromide at ambient temperature leads to very high yields of allenes; when cyclopropylidene-allene ring opening is suppressed, alternative carbenic products are observed, although other reactions compete. When the reactions are carried out at -60°C, a 1-bromo-1-(bromomagnesio)-cyclopropane is formed which may be trapped by a number of electrophiles.
