Solvolysis of the novel bridgehead cyclobutyl methyl chloride proceeds without skeletal rearrangement. Its relative rate is the first unequivocal proof for a small, but significant ability of the cyclobutyl group to stabilize an adjacent positively charged center.
Alternative synthetic routes are provided to synthesize γ-amino acids in their free form or conveniently protected for their selective incorporation into ramified γ-peptides with a cyclobutane core. The key synthetic-step involves the stereoselective conjugate addition of nitromethane to chira...
A novel class of 4-alkoxy-[1′-cyclobutyl-spiro(3,4-dihydrobenzopyran-2,4′-piperidine)] analogues were designed and synthesized as H3R antagonists. Structure–activity relationship identified sulfone 27 with excellent H3R affinities in both humans and rats, and acceptable pharmacokinetic proper...
Cyclobutyl phenyl sulfide 2, cyclobutyl phenyl sulfoxide 3 and (SR)-cyclobutyl p-tolyl sulfoxide (SR)-8 have been synthesized and used for the spiroannelation of cyclopentanone. In the most effective sequence, lithiated 3 is added to ketones with formation of β-hydroxy sulfoxides 4a-g, which ar...
Four platinum(II) complexes of N-cyclobutyl-1R,2R-diaminocyclohexane with different bidentate dicarboxylates (1 oxalate, 2 malonate, 3 1,1-cyclobutanedicarboxylate and 4 3-hydroxy-1,1-cyclobutanedicarboxylate) as leaving groups were synthesized and characterized by elemental analyses, IR and 1HN...
The heat capacity of crystalline and liquid methylenecyclobutane has been measured in the temperature range 12 to 315 K. Its vapour pressure from 293 to 306 K and its enthalpy of fusion under reference conditions have also been determined. The functions “Ho(T) − Ho(0)’, So(T), and “Go(T) − Ho...
The reaction of methylenecyclobutane (1) with bis(acetonitrile)chloronitropalladium(II) in methylene chloride yields cyclopentanone. Two intermediates - π-olefin complex of palladium and product of β-nitritopalladation of 1 in a Markovnikov fashion - are observed by 1H and 13C NMR. Palladium-c...
We report herein stereoselective additions of a nitrene derived from PhI(OAc)2 and 2,4-dinitrophenylsulfenamide with methylenecyclopropanes (MCPs) and a methylenecyclobutane (MCB) to give the corresponding ring enlargement products, (cyclobutylidene)amide or (cyclopentylidene)amide derivatives, ...
SummaryFused methylenecyclobutanes comprise a new free radical ring expansion system leading to cis-fused methylenecycloheptanes
The catalytic asymmetric [2+2] cycloaddition proceeds between 3-(2-alkenoyl)-1, 3-oxazolidin-2-ones and 1, 2-propadienyl sulfides having various substituents at 1-position, affording methylenecyclobutane derivatives with high optical purity. Seven and eight membered carbocycles with chiral side ...
The reaction of ethyl nitrodiazoacetate with a series of methylenecyclobutanes was studied and both [1+2]- and [2+3]-cycloaddition pathways were observed depending on olefin structure. Amino acids of a spirohexane type were synthesized from methylenecyclobutanes by a three-step synthesis.
The mono-aryl substituted methylenecyclobutanes undergo an interesting reaction with diphenyl diselenide in the presence of iodosobenzene diacetate and H2O at 40 °C in 1,2-dichloroethane to give the corresponding aryl-(1-phenylselanylcyclobutyl)methanones in moderate to good yields within 30 h....
Methylenecyclobutanes undergo a lithiation reaction in the presence of n-BuLi or n-BuLi/KOtBu from −78 °C to room temperature or to 40 °C in THF within 3 h and then quenching with a variety of electrophiles to give the corresponding addition products (alcohols) in moderate to good yields withi...
Methylenecyclobutanes undergo an interesting rearrangement reaction in the presence of silver acetate and iodine at room temperature (20 °C) in dichloromethane to give the corresponding aryl-(1-arylcyclobutyl)methanones in good to high yields within short reaction time. A plausible reaction mec...
This study reports the synthesis and the two-photon absorption (TPA) properties of a series of 9,10-anthracene-centred oligo(p-phenyleneethynylene)s with end-capping didecylamine. The results show that both the maximal TPA cross-sections (δmax) and the fluorescence quantum yields (Φ) of the ol...
The percentage extraction of the elements U(VI), Mo(VI), Zr(IV) and Sr(II) from 1–6 M nitric acid by trioctylamine (TOA) and its radiolytic degradation products dioctylamine (DOA) and primary octylamine (POA) in xylene have been measured. TOA and DOA showed similar extraction capacities for Zr(...
Cationic acetylacetonate bis(secondary amine) palladium (II) complexes were synthesized by nitrile substitution of [Pd(acac)(MeCN)2][BF4] with L (L = morpholine, diethylamine, dibutylamine, dioctylamine) which yielded [Pd(acac)(L)2][BF4] as a mononuclear species with chelating acac ligand. An X-...
In this study, the effect of Pb(NO3)2 on the flotation behavior of scheelite using sodium oleate (NaOL) as a collector in the presence and absence of Ca2+ ions was investigated through the micro-flotation tests, solution chemistry calculation, zeta potential measurements, and FT-IR analysis. The...
The flotation behaviors of ilmenite untreated or treated with lead ions using sodium oleate as a collector were studied. The results of micro-flotation experiments reveal that ilmenite shows good floatability at pH 6–8. Compared with the flotation recovery of ilmenite untreated with lead ions, ...
This paper proposed the surface modification of hemimorphite using lead ions as a promising method for increasing its flotation recovery with sodium oleate as collector. The floatability of lead-modified hemimorphite was significantly improved and the flotation recovery of hemimorphite in the pr...
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