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A new convenient synthetic procedure for the preparation of tri- and tetrafluoropropanamides derived from sugars has been described. The conformations of fluorinated amides calculated for isolated molecules and those in the crystal state have been compared. In contrast to single α-fluorine substituted amides, which preferred the anti conformation around the F–C–C=O bond, for tetrafluorinated amides the additional trifluoromethyl group forces the conformation of the F–C–C=O bond to be nearly syn. [ABSTRACT FROM AUTHOR]

The zooplankton of a meromictic lake,in a former limestone quarry situated in southern Poland,was studied monthly in the years 2000-2001.A low density and diversity of zooplankton assemblage was noted. Individuals of the dominant species Daphnia longispina represented all body size classes and were present during the whole study period: the maximum number of Daphnia females carrying the eggs was noted in May.The normal dial vertical migration of Daphnia ,studied in June,was observed. [ABSTRACT FROM AUTHOR]

New gem -difluoroalkenes were synthesized by the dehydrofluorination of the corresponding 4-CF 3 -β-lactams. An unexpected rearrangement mechanism of the ester moiety dependent on a stabilizing negative charge was observed. Hydrogenation to 4-CHF 2 -β-lactams was successful from gem -difluoro-β-lactams.

Herein, we would like to present deoxyfluorinating reagents such as DAST and PyFluor and their successful use as tools for selective modification of γ-amino-α-hydroxyphosphonates. Depending on the deoxyfluorinating reagent applied, an intramolecular cyclization leading to phosphonates containing the 1,3-oxazinan-2-one moiety or direct nucleophilic deoxyfluorination yielding the α-fluorinated derivatives of γ-aminophosphonates was observed. The obtained compounds may be used as precursors in the preparation of medicinally important compounds e.g. , dipeptide analogues or scaffolds containing the 1,3-oxazinan-2-one group.

The application of DFT computational method (B3LYP/6-311++G(d,p)) to mono- and poly(CF 3 )substituted naphthalene derivatives helps to study changes in the electronic properties of these compounds under the influence of 11 substituents (-Br, -CF 3 , -CH 3 , -CHO, -Cl, -CN, -F, -NH 2 , -NMe 2 , -NO 2 , and -OH) to confront substituent effects in naphthalene with an analogous situation in benzene. This paper shows the dependencies of theoretically calculated SESE (Substituent Effect Stabilization Energy) values on empirically determined, well-defined Hammett-type constants ( σ p , σ m , R , and F ). Described poly(CF 3 )substituted derivatives of naphthalene are, so far, the most sensitive molecular probes for the substituent effects in the aromatic system. The presence of the trifluoromethyl groups of such an expressive nature significantly increases the sensitivity of the SESE to changes caused by another substitution. Further, the more -CF 3 groups are attached to the naphthalene ring, the more sensitive the probe is. Certain groups of probes show additivity of sensitivity: the obtained sensitivity relates to the sum of the sensitivities of the mono(CF 3 )substituted probes.

A one-pot, regioselective 1,3-dipolar cycloaddition of in situ generated (diethoxyphosphoryl)difluoromethyl nitrile oxide toward selected alkenes and alkynes is reported. This protocol enables facile access to 3,5-disubstituted isoxazolines and isoxazoles bearing a CF2P(O)(OEt)2 moiety in good to excellent yields, under mild reaction conditions.

The synthesis of the stable surrogates of an important amino acid ( R )-4-amino-3-hydroxybutyric acid (GABOB) such as substituted hydroxy aminophosphonic acids bearing a quaternary stereogenic center is presented. Highly diastereoselective formations of fluorinated spiroepoxy alkylphosphonate or related tertiary carbon-containing oxiranes from β-keto phosphonates possessing methyl, phenyl, or cyclohexenyl substituents, are reported. Stereoselective acid-promoted epoxide opening by bromide or azide followed by reduction/protection afforded tertiary bromides or N -Boc derivatives of β-amino-γ-hydroxy alkylphosphonates in most cases, while the reactions of oxiranes with different amines yielded their β-hydroxy-γ-amino regioisomers. Surprisingly, during the synthesis of amino phosphonic acids, we observe that the acid-induced rearrangement proceeded in a high diastereospecific manner, leading finally to substituted β-hydroxy-γ-aminoalkylphosphonic acids., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Rapp, Margas-Musielak, Kaczmarek, Witkowska, Cytlak, Siodła and Koroniak.)

Herein, we present an efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates. Each step of the synthesis was optimized to provide excellent yields. Moreover, the absolute configuration of the obtained compounds was determined by X-ray analysis, which proved the stereochemistry that was proposed based on NMR studies., (Copyright © 2020, Kaźmierczak and Koroniak; licensee Beilstein-Institut.)