82168-14-7Relevant articles and documents
Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols
Shi, Chang-Yun,Yin, Liang,Zhang, Qi,Zhou, Si-Wei
supporting information, p. 26351 - 26356 (2021/11/09)
By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.
Pentadienyl type lithium and potassium species: The regioselectivity of their reactions with electrophiles
Schlosser,Zellner,Leroux
, p. 1830 - 1836 (2007/10/03)
Seven structurally distinct pentadienyl type lithium and potassium compounds were screened against a variety of electrophiles in order to assess the regioselectivity of the trapping reactions. Organoborates and analogs thereof (fluorodimethoxyborane) proved to be perfectly regioreliable attacking only unsubstituted terminal positions and thus providing, after oxidation, exclusively primary allylic alcohols. 2,4-Pentadienyllithiums or -potassiums, that carry a methyl group at the 1- or 3-position, exhibit the same extreme regioselectivity towards halotrialkylsilanes or carbon dioxide. Although the unsubstituted parent compounds combine with such electrophiles still preferentially at the terminal position, considerable proportions of branched products are concomitantly formed as well (1/3-attack ratios ranging from 2:1 to >20:1). Hydroxyalkylating and alkylating reagents such as formaldehyde, oxirane or butyl iodide invariably afford regioisomeric mixtures generally varying in composition between 3:1 and 1:3. The condensation reaction with halotrialkylsilanes appears to follow a concerted (SN2-like) rather than an addition/elimination (ate complex-mediated) mechanism.
An Approach to Cytochalasan Synthesis: Macrolide Formation by an Intramolecular Diels-Alder Reaction. X-Ray Structure of Methyl (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate
Bailey, Stephen J.,Thomas, Eric J.,Vather, Sunil M.,Wallis, John
, p. 851 - 860 (2007/10/02)
When heated in toluene under reflux, under high dilution conditions, trans,trans-hexadeca-12,14-dienoyl-oxymaleic anhydride (4) cyclised via an intramolecular Diels-Alder reaction to give the macrocyclic lactone (5) in 27percent yield together with 5percent of a regioisomer (23). (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-octanoyloxycyclohex-3-ene-1,6-dicarboxylic acid anhydride (11) was converted into the methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-octanoyloxy-6-benzylcarbonylcyclohex-3-ene-1-carboxylate (33), but selective reduction of this ketone was unsuccessful.The structure of one of the reduction products, methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate (35) was confirmed by an X-ray structure determination.
