1,1,1,4,5,5,5-Heptafluoro-4-(trifluoromethyl)-2,3-pentanedione,a potent reagent for the synthesis of cyclic λ5σ5 phosphoranes

1,1,1,4,5,5,5-Heptafluoro-4-(trifluoromethyl)-2,3-pentanedione reacted with λ³σ³-phosphorus compounds, PR¹R²R³ (R¹ = CF₃, R² = R³ = Me, iPr, NEt₂; R¹ = NCO, R² = R³ = OMe, OEt, R²−R³ = OCH₂CH₂O, OCMe₂CMe₂O; R¹ = OSiMe₃, R² = R³ = OEt; R¹ = NEt₂, R² = R³ = OCH₂CF₃; R¹ = R² = Et₂N, R³ = OCH₂CF₃, OCH(CF₃)₂, OCH₂Ph, OC₆F₅) to give new 1,3,2λ⁵σ⁵-dioxaphospholenes. The first λ⁵σ⁵ phosphoranes with an OCN group bonded to phosphorus were obtained. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:109–113, 1998     

d,h-μ-Benzylalkoxophosphonato-e-μ-alkoxo-f-μ-oxo-bis[trichloroantimon(V)]-Verbindungen

d, h-μ-Benzylalkoxophosphonato-e-μ-alkoxo-f-μ-oxo-bis[trichloroantimony(V)] Compounds The binuclear antimony(V) complexes Cl₃Sb(O)[R³(R¹O)PO₂](OR²)SbCl₃ 1 – 6 with R¹ = R² = CH₃, C₂H₅ and R³ = C₆H₅CH₂, (CH₃)₃C₆H₂CH₂ in solution slowly exchanges the R² groups between the oxygen atoms of the Sb₂O₂ ring. The SbOPOSb ringsystem makes rapid pseudorotation. The isomeres are detected by nmr spectroscopy. 1 (R¹ = R² = CH₃) crystallizes in the orthorhombic space group Pnma with a = 1247.0, b = 1324.1, c = 1207.9 pm and Z = 4. 2 (R¹ = CH₃, R² = C₂H₅) and 5 (R¹ = R² = CH₃, R³ = (CH₃)₃ · C₆H₂CH₂) crystallizes triclinic in the space group P-1 with a = 984.1, b = 1026.7, c = 1079.9 pm, α = 87.93, β = 75.70, γ = 87.62° and Z = 2 and a = 1164.6, b = 1296.9, c = 1712.9 pm, α = 109.9, β = 96.3, γ = 100.2° and Z = 4 resp., with two crystallographically independent molecules in the asymmetric unit.     

S,N,N′-Substituted sulfurdiimines as ligands: II. Compounds [(ν3-RC3H4)Pd{R1NS(R2)NR1}] (R  H,CH3;R1  aryl; R2  CH3, t-C4H9) and some related triazenido and amidino compounds of palladium(II)

The complexes [(ν³-RC₃H₄)Pd{R¹NS(R²)NR¹}] (R  H, CH₃;R¹  aryl; R²  CH₃, t-C₄H₉) have been obtained from the reaction of [(ν³-RC₃H₄)PdCl]₂ with [Li{R¹NS(R²)NR¹}]; two isomers are produced, differing in the orientation of the allyl group. The sulfurdiimino group has some π-allylic character. The compounds decompose in solution into azo—arenes and [(ν³-RC₃H₄)Pd(SR²)]₂, and this is shown to be dependent upon steric and electronic factors.The properties of the sulfurdiimino compounds are compared with those of the compounds [(ν³-RC₃H₄)Pd(R³N₃R³)]₂ and [(ν³-RC₃H₄)Pd(R³NC(R⁴)NR³)]₂ (R  H, CH₃;R³  CH₃, aryl; R⁴  H, CH₃), which have been prepared by new methods.     

Collision-induced dissociations of deprotonated peptides,dipeptides and tripeptides with hydrogen and alkyl α groups. An aid to structure determination

The characteristic collision-induced dissociations of [M ? H]^? ions of dipeptides and tripeptides involve proton transfer to the carboxylate centre as a prelude to fragmentation. Dipeptides show the process NH₂CH(R¹)CONHCH(R²)CO₂^? → NH₂C(R¹)CONHCH(R²)CO₂H → ^?NHCH(R²)CO₂H + NH₂C(R¹)?C?O (R = H or alkyl) while tripeptides show the analogous processes NH₂CH(R¹)CONHCH(R²)CONHCH(R³)CO₂^? → NH₂CH(R¹)CONHC(R²)CONHCH(R³)CO₂^? → NHCH(R³)CO₂H + NH₂CH(R¹)CONHC(R²)?C?O and NH₂CH(R¹)CONHCH(R²)? CONHCH(R³)CO₂^? → NH₂C(R¹)CONHCH(R²)CONHCH(R³)CO₂H → ^?NHCH(R²)CONHCH(R³)CO₂H + NH₂C(R¹)?C?O. These fragmentations provide ready identification of the peptide.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

Reactions of the fluorinated amines (CF₃)₂NH, CF₃N(OCF₃)H, CF₃N[OCF(CF₃)₂]H, CF₃NHF and SF₅NHF with the strong acid HF/AsF₅ form the corresponding ammonium salts R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=CF₃, SF₅] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ～5 torr (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

Unimolecular reactions of the isolated immonium ions CH3CH = NH+C4H9, CH3CH2Ch = NH+C4H9 and (CH3)2C = NH+C4H9

The reactions of ten metastable immonium ions of general structure R¹R²C?NH⁺C₄H₉ (R¹ = H, R² = CH₃, C₂H₅; R¹ = R² = CH₃) are reported and discussed. Elimination of C₄H₈ is usually the dominant fragmentation pathway. This process gives rise to a Gaussian metastable peak; it is interpreted in terms of a mechanism involving ion-neutral complexes containing incipient butyl) cations. Metastable immonium ions ontaining an isobutyl group are unique in undergoing a minor amount of imine (R¹R²C?NH) loss. This decomposition route, which also produces a Gaussian metastable peak, decreases in importance as the basicity of the imine increases. The correlation between imine loss and the presence of an isobutyl group is rationalized by the rearrangement of the appropriate ion-neutral complexes in which there are isobutyl cations to the isomeric complexes containing the thermodynamically more stable tert-butyl cations. A sizeable amount of a third reaction, expulsion of C₃H₆, is observed for metastable n-C₄H₉ ⁺NH?CR¹R² ions; in contrast to C₄H₈ and R¹R²C?NH loss, C₃H₆ elimination occurs with a large kinetic energy release (40–48 kJ mol^?1) and is evidenced by a dish-topped metastable peak. This process is explained using a two-step mechanism involving a 1,5-hydride shift, followed by cleavage of the resultant secondary open-chain cations, CH₃CH⁺ CH₂CH₂NHCHR¹R².     

Mass spectra of esters of α-hydroxy and α-methoxy acids

The most abundant fragment produced by electron bombardment of esters of the type R¹R²C(OR³)CO₂R⁴ is the R¹R²C = \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm O}\limits^{{\rm + } \cdot } $\end{document}R³ ion. Methyl glycollate (R¹ = R² = R³ = H, R⁴ = Me) eliminates the HCO˙ radical by a complex rearrangement involving the methylenic hydrogen atoms. The methyl and ethyl esters of methoxyacetic acid (R¹ = R² = H, R³ = Me, R⁴ = Me or Et) eliminate formaldehyde by the McLafferty rearrangement.     

New one-pot, efficient, and regioselective method for the synthesis of 3-Trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs

An efficient and regioselective procedure for the synthesis of a series of alkyl(aryl/heteroaryl) substituted 3-trifluoromethyl-1H-1-phenylpyrazoles and alkyl 3-carboxylate analogs, from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihaloalk-3-en-2-ones [CX₃C(O)CR²=CR¹(OMe/OEt), where R¹ = H, Me, Ph, 2-Furyl; R² = H; R¹-R² = -C₄H₈- and X = F, Cl] and 1-phenylsemicarbazide in an acidified alcoholic medium (R³OH/H₂SO₄), where R³ = Me, Et, Prⁱ was successfully applied and is described here in detail.     

Formation of 5-phenyl-1,2-dithiole-3-thione from molybdenum dithiopropiolato complexes

Molybdenum dithiopropiolato complexes, [(η⁵-C₅R₄R^′)Mo(CO)₂(η²-S₂CCCPh)] (R=H, R^′=Me 1a, R=R^′=H 1b; R=R^′=Me 1c) react with trimethylamine-N-oxide (TMNO · 2H₂O) under mild thermolysis to form 5-phenyl-1,2-dithiole-3-thione (2). The reaction proceeds through the formation of the oxo-complexes, [(η⁵-C₅R₄R^′)Mo(O)(η³-S₂CCCPh)] (R=H, R^′=Me 3a, R=R^′=H 3b; R=R^′=Me 3c). Direct reaction of 3a-c with TMNO · 2H₂O under thermolysis also results in formation of 2.     

Configuration-Interaction study of lower excited states of O2: Valence and rydberg characters of the two lowest 3Σu − states

Configuration-interaction calculations, with an extended basis, are carried out on the ground and lower excited states of O₂ and O₂⁺ at and near the equilibrium internuclear distance (R = 2.3 a.u.) of the ground state of O₂. Particular attention has been paid to the two lowest ³Σ_u^? states, and the mixing of the valence and Rydberg characters in these states are studied. The lowest ³Σ_u^? state is a Rydberg-type state for R < 2.3 a.u., but becomes valence-type for R ? 2.3 a.u. The second ³Σ_u^? state, which is 1.6 eV above the lowest ³Σ_u^? at R = 2.3 a.u., changes its character from Rydberg to valence, valence to Rydberg, and then to valence again when R increases from 1.9 to 3.1 a.u. Satisfactory agreement between the calculated and experimental vertical excitation energies is obtained.     

Influence of the nature of ligands in iridium complexes with C60 fullerene and ·P(O)(OPri)2, ·CMe3, and ·CCl3 radicals on regioselectivity of addition and stability of spin-adducts formed: an EPR study

The addition of ^·P(O)(OPrⁱ)₂ (R¹), ^·CMe₃ (R²), and ^·CCl₃ (R³) radicals to metallofullerenes (η²-C₆₀)IrH(CO)(CNBu^t)₂(o-HCB₁₀H₉CCH₂PPh₂-B,P) (1), (η²-C₆₀)IrH(CO)(DIOP) (DIOP is (4R,5R)-(+)-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxolane, 2), and (η²-C₆₀)IrH(CO)(PPh₃)₂ (3) was studied by EPR spectroscopy. A stability study of spin adducts (SAs) of R¹ radicals with complexes 1 and 2 showed that when the reactions are initiated by illumination with 366-nm light, the EPR spectra exhibit only signals of those isomers that are formed upon attack of the R¹ radicals on the carbon atoms of the cis-1 and cis-2 bonds (i.e., carbon atoms of the fullerene hemisphere to which the metallofragment is attached). Investigations of the reactions of R² and R³ radicals with complexes 1–3 initiated with 366-nm light made it possible to detect (i) regioisomers formed by adding these radicals to carbon atoms of the cis-n bonds and (ii) SAs formed by adding the radicals to carbon atoms of other bonds in complexes 1–3. The hyperfine structure of the EPR spectrum essentially depends on the spatial structure of substituents at the metal atom and allows individual regioisomers of not only phosphoryl radicals, but also carbon-centered radicals R² and R³ with metallofullerenes 1–3 to be identified. The rate constants for addition of R² and R³ radicals to complexes 2 and 3 were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1302–1309, July, 2007.     

Stereoselective generation of cis-2-lithio-3-CF3-oxirane via CF3-substituted β-oxido carbenoids. Highly stereoselective synthesis of CF3-substituted tri- and tetrasubstituted oxiranes and tetrasubstituted alkenes

Treatment of 2-substituted 3,3-dichloro-1,1,1-trifluoropropan-2-ols with organolithium reagents R²Li in THF at −98°C stereoselectively produces 2,3-disubstituted 2-lithio-3-trifluoromethyloxiranes with Li and CF₃cis. The reagents react with electrophiles El-X or organoboranes R³BR₂ to give CF₃-containing tri- and tetrasubstituted oxiranes or tetrasubstituted alkenes, respectively, with high diastereoselectivities.     

Isomere η2-Acyl- und σ-Alkyl(carbonyl)-Komplexe von Molybdän und Wolfram. Eine Studie zum Bildungs-mechanismus,zur Isomerisierungsgeschwindigkeit und zur Steuerung der Gleichgewichtslage

η²-Acyl and σ-Alkyl(carbonyl) Coordination in Molybdenum and Tungsten Complexes: Synthesis and Studies of the Isomerization Equilibria and Kinetics The anionic molybdenum and tungsten complexes [L_RM(CO)₃]^? (L_R^? = [(C₅H₅)Co{P(O)R₂}₃]^?, R = OCH₃, OC₂H₅, O-i-C₃H₇; M = Mo, W) have been alkylated with the iodides R′ I, R′ = CH₃, C₂H₅, i-C₃H₇, and CH₂C₆H₅. The reactivity pattern of the alkylation is in accord with a S_N2 mechanism. Depending on M, R′, reaction temperature, and time the η-alkyl (carbonyl) compounds [L_RM(CO)₃R′] and/or the isomeric η²-acyl compounds [L_RM(CO)₂(η²-COR′)] can be obtained. 8 new σ-alkyl(carbonyl) compounds and 15 new η²-acyl compounds have been isolated and characterized. The ¹H NMR and the IR spectra give conclusive evidence that the σ-alkyl(carbonyl) compounds [L_RM(CO)₃R′] are formed as the primary products of the alkylation and that they isomerize partly or completely to give the η²-acyl compounds [L_RM(CO)₂(η²-COR′)]. The position of the equilibrium σ-alkyl(carbonyl)/η²-acyl is controlled by the steric demands of the groups R′ and the ligands L_R^?. The molybdenum compounds isomerize much more readily than the tungsten compounds. The rate constants of the isomerization processes [L_RMo(CO)₃CH₃] → [L_RMo(CO)₂(η²-COCH₃)], R = OCH₃, OC₂H₅, and O-i-C₃H₇, measured at 305 K in acetone-d₆, are 6–8 x 10^?3 s^?1.     

Reactivity of radicals CCl3(CH2CHR)n (R=H,CH3, Cl; n=1, 2) in addition reactions with unsaturated compounds

Using EPR spectroscopy, the rate constants for the addition of radicals CC1₃(CH₂· CH₂)_n, (R¹ for n=1 and R² for n=2), CCl₃CH₂CHCH₃ (R³), and CCl₃CH₂CHCl (R⁴) to unsaturated compounds CH₂=CHX (X=C₆H₅, COOCH₃, CN) and CH₂=C(CH₃)Y (Y=C₆H₅, COOCH₃) at 22C have been determined. The radicals R¹ and R² exhibit ambiphilic, and R⁴ electrophilic character towards the selected unsaturated compounds. It has been shown that the presence of the CCl₃ group in the -position of the radical center has little effect on the reactivity of the radical. Replacement of a hydrogen on the -carbon in radical R¹ by a CH₃ group or chlorine atom leads to a considerable reduction in the rate of addition of the radicals to the unsaturated compounds examined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 548–554, March, 1991.     

Bis(arylimido) Molybdenum(VI) Amidinate and Guanidinate Complexes; Molecular Structures of [(ArN)2MoMe{N(Cy)C[N(i‐Pr)2]N(Cy)}] (Ar = 2,6‐i‐Pr2C6H3; Cy = Cyclohexyl) and [(2,6‐i‐Pr2C6H3N)2MoCl2] · [NH=C(C6H5)CH(SiMe3)2]

The reaction of [(ArN)₂MoCl₂] · DME (Ar = 2,6‐i‐Pr₂C₆H₃) ( 1 ) with lithium amidinates or guanidinates resulted in molybdenum(VI) complexes [(ArN)₂MoCl{N(R¹)C(R²)N(R¹)}] (R¹ = Cy (cyclohexyl), R² = Me ( 2 ); R¹ = Cy, R² = N(i‐Pr)₂ ( 3 ); R¹ = Cy, R² = N(SiMe₃)₂ ( 4 ); R¹ = SiMe₃, R² = C₆H₅ ( 5 )) with five coordinated molybdenum atoms. Methylation of these compounds was exemplified by the reactions of 2 and 3 with MeLi affording the corresponding methylates [(ArN)₂MoMe{N(R¹)C(R²)N(R¹)}] (R¹ = Cy, R² = Me ( 6 ); R¹ = Cy, R² = N(i‐Pr)₂ ( 7 )). The analogous reaction of 1 with bulky [N(SiMe₃)C(C₆H₅)C(SiMe₃)₂]Li · THF did not give the corresponding metathesis product, but a Schiff base adduct [(ArN)₂MoCl₂] · [NH=C(C₆H₅)CH(SiMe₃)₂] ( 8 ) in low yield. The molecular structures of 7 and 8 are established by the X‐ray single crystal structural analysis.     

Metabolism of Deuterated threo‐Dihydroxy Fatty Acids in Saccharomyces cerevisiae: Enantioselective Formation and Characterization of Hydroxylactones and γ‐Lactones

Biotransformation of (±)‐threo‐7,8‐dihydroxy(7,8‐²H₂)tetradecanoic acids (threo‐(7,8‐²H₂)‐ 3 ) in Saccharomyces cerevisiae afforded 5,6‐dihydroxy(5,6‐²H₂)dodecanoic acids (threo‐(5,6‐²H₂)‐ 4 ), which were converted to (5S,6S)‐6‐hydroxy(5,6‐²H₂)dodecano‐5‐lactone ((5S,6S)‐(5,6‐²H₂)‐ 7 ) with 80% e.e. and (5S,6S)‐5‐hydroxy(5,6‐²H₂)dodecano‐6‐lactone ((5S,6S)‐5,6‐²H₂)‐ 8 ). Further β‐oxidation of threo‐(5,6‐²H₂)‐ 4 yielded 3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ), which were converted to (3R,4R)‐3‐hydroxy(3,4‐²H₂)decano‐4‐lactone ((3R,4R)‐ 9 ) with 44% e.e. and converted to ²H‐labeled decano‐4‐lactones ((4R)‐(3‐²H₁)‐ and (4R)‐(2,3‐²H₂)‐ 6 ) with 96% e.e. These results were confirmed by experiments in which (±)‐threo‐3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ) were incubated with yeast. From incubations of methyl (5S,6S)‐ and (5R,6R)‐5,6‐dihydroxy(5,6‐²H₂)dodecanoates ((5S,6S)‐ and (5R,6R)‐(5,6‐²H₂)‐ 4a ), the (5S,6S)‐enantiomer was identified as the precursor of (4R)‐(3‐²H₁)‐ and (2,3‐²H₂)‐ 6 ). Therefore, (4R)‐ 6 is synthesized from (3S,4S)‐ 5 by an oxidation/keto acid reduction pathway involving hydrogen transfer from C(4) to C(2). In an analogous experiment, methyl (9S,10S)‐9,10‐dihydroxyoctadecanoate ((9S,10S)‐ 10a ) was metabolized to (3S,4S)‐3,4‐dihydroxydodecanoic acid ((3S,4S)‐ 15 ) and converted to (4R)‐dodecano‐4‐lactone ((4R)‐ 18 ).     

Crystal structures of CrH2P3O10 and InH2P3O10

The crystal structures of chromium and indium dihydrogen triphosphates, CrH₂P₃O₁₀ and InH₂P₃O₁₀, in modification II are refined by the Rietveld method using X-ray powder diffraction data. The compounds crystallize in the monoclinic crystal system, space group P21/n. Z = 4, a = 7.3225(4)Å, b = 8.6835(6)Å, c = 11.6599(7) Å, and b = 102.388(3)° for CrH₂P₃O₁₀, and a = 7.5332(1)Å, b = 9.0841(1)Å, c = 11.8600(1) Å, and b = 103.9596(7)° for InH₂P₃O₁₀. The structures are refined in the isotropic approximation (pseudo-Voigt profile function): R_p = 4.8%, R_wp = 6.9%, R_Bragg = 7.5%, R_F = 9.9% for CrH₂P₃O₁₀; R_p = 6.3%, R_wp = 8.3%, R_Bragg = 6.2%, R_F = 4.1% for InH₂P₃O₁₀. The crystal structures of compounds in the isostructural series M^IIIH₂P₃O₁₀-II, where M^III = Al, Ga, Cr, V, Fe, and In, are examined and compared.     

Organosilicon Amine Gels Based on 3-Aminopropyltriethoxysilane, Cobalt(II) or Chromium(III) Clorides, and Triethoxysilane

Organosilicon gels [Co(NH₂R²)₂Cl₂] and [Cr(NH₂R²)₃Cl₃], containing a diaminodichloride complex of cobalt(II) and triaminotrichloride complex of chromium(III) (R² = CH₂CH₂CH₂SiO(OEt)), were synthesized by the hydrolysis of complexes [Co(NH₂R¹)₂Cl₂] (I) and [Cr(NH₂R¹)₃Cl₃] (II) incorporating peripheral triethoxysilyl groups (R¹ = CH₂CH₂CH₂Si(OEt)₃). The coprecipitated [Co(NH₂R²)₂Cl₂] · 4NH₂R³, [Cr(NH₂R²)₃Cl₃] · 6NH₂R³, [Co(NH₂R²)₂Cl₂] · 2SiO₂, and [Cr(NH₂R²)₃Cl₃] ·xSiO₂ · (3 – x)SiHO_1.5 (R³ = CH₂CH₂CH₂SiO_1.5) gels were obtained by cohydrolysis of complexes I and II with 3-aminopropyltriethoxysilane or triethoxysilane. Interaction with SiH(OEt)₃ is accompanied by the decomposition of silicon hydride groups and the formation of tetraethoxysilane derivatives. The heating of dry gels in a flow of argon or oxygen to 600° results in the formation of amorphous silica having a specific surface area 2–467 m²/g and containing crystalline metals, their chlorides, oxides, silicates, or carbides.     

Syntheses of σ-cyclobut-1-en-3-onyl complexes by cycloaddition of ketenes to some transition metal alkynyl complexes

Reactions of ketenes (R¹R²CCO) with (η⁵-C₅H₅)Ni(PPh₃)CCR (I) and (η⁵-C₅H₅)Fe(CO)(L)CCR (III, L = CO and PPh₃) give σ-cyclobut-1-en-3-onyl complexes, {(η⁵-C₅H₅)Ni(PPh₃)$\text{CC(R)COC}$}R¹R² (VI) and (η⁵-C₅H₅)Fe(CO)(L)$\text{CC(R)COC}$R¹R² (IX)}, (2 + 2) cycloaddition products, in good yields. The σ-cyclobutenonyl complexes also can be prepared by the reaction of I and III with acyl chlorides in the presence of triethylamine.     

Tipranavir analogous 3-sulfonylanilidotetronic acids: new synthesis and structure-dependent anti-HIV activity

Sulfonamide-containing tetronic acids 1, structural analogues of the HIV-1 protease inhibitor tipranavir, were synthesised in five steps including a microwave-assisted Claisen rearrangement of cinnamyl tetronates and a modified Charette cyclopropanation of the so-formed 3-allyltetronic acids. Compounds 1 with two non-H residues (R¹, R²) at C-5 of the tetronate core exhibited structure-dependent antiviral activity in two HIV strains. Derivatives 1c (R¹=R²=Me, R³=Cl) and 1d (R^1,2=(CH₂)₅, R³=Me) were most active (IC₅₀<10 μM) in the sensitive strain HIV_NL4-3.