Chemical Synthesis,Proton NMR. Parameters,Hydrogen- and Calcium-Ion. Complexation of L-γ-Carboxyglutamyl-L-γ-carboxyglutamic Acid and D-γ-Carboxyglutamyl-L-leucine

The purpose of this communication is to describe the preparation and some properties of the first two synthetic peptides containing D - and L -γ-carboxyglutamic acid. Use was made of N-protected γ,γ′-di-t-butyl-γ-carboxyglutamic acids (D , L , and DL ) described earlier [1 a]. Preliminary ¹H-NMR. data (360 MHz) indicate a restricted rotation of the Gla side chain in the free amino acid as well as in the C-terminal Gla of Gla-Gla in H₂O solution at acid pH. The proton dissociation from Gla and Gla-Gla was studied by potentiometric titration and NMR. methods. The pH titration in the presence of Ca²⁺ ions shows that Gla-Gla has a much higher association constant for this cation than Gla. It is almost as great as that of prothrombin (pCa²⁺ = 3.2 vs. 3.5).     

Substituted γ-lactones. XXX. Reactions of α-Keto-β-Subtituted-γ-butyrolactones with diamines

The condensation reaction between α-keto-β-aroyl (or acyl) -γ-butyrolactones, 4a-4e and o-phenylenediamine or 2, 3-diaminonaphthalene leads under retrograde aldol condensation involving loss of formaldehyde to formation of 3-substituted-3, 4-dihydro-2 (1H) quinoxalinones or benzo [g] quinoxalinones, 7a-7g , respectively as a new convenient synthesis of this type of heterocyclic systems. The reaction of type 4 compound with 4, 5-diaminopyromidine, 8 , was found to proceed differently. 2-[(4-Amino-5-pyrimidinyl)amine]-4-oxo-3-(hydroxymethyl)-4-phenyl-2-butenoic acid 9 was the only product formed when the reaction between 4a and 8 was run in ethanol. The same reaction in glacial acetic acid proceeds with loss of formaldehyde, to afford 7-phenacylidene-7,8-dihydro-6 (1H)-pteridione 10 . The reaction between type 4 compounds and ethylenediamine or 1, 4-phenylenediamine leads to the formation of the bis-condensation products 13–15 , respectively.     

Soluble bimetallic μ-oxoalkoxides. IX. ε-caprolactone and β-propiolactone block copolymerization

The fast and living ring-opening polymerization of lactones by bimetallic μ-oxoalkoxides in homogeneous organic phase has led to successful block copolymerization. The catalyst is coordinatively associated in organic media; however, interaction with lactones can induce, following their nature, different rearrangements of the catalytic aggregates, depending on the nature of these lactones. Consequently, ε-caprolactone and β-propiolactone block copolymers are quantitatively obtained only in the presence of a completely dissociated catalyst.     

γ-Radiolysis of ketone polymers. II. γ-Irradiation of styrene–methyl vinyl ketone copolymers

γ-Radiolysis of copolymers of styrene and methyl vinyl ketone shows that the introduction of pendant carbonyl groups markedly increases the G(s) value as compared to the homopolymer of styrene. The G(x) value is only slightly affected. These efficiencies are determined by employing an established statistical theory for random crosslinking and scission coupled with gel-permeation chromatography as the analytical tool required to follow the changes in the MWD of polymers. Also the G(H₂) values are unaltered by the introduction of carbonyl groups in polystyrene. These results are in marked contrast to the effects of carbonyl groups in polyethylene when subjected to γ-radiolysis and can be attributed to the protective role played by the aromatic phenyl groups in polystyrene.     

Photochemie von tricyclischen β, γ-γ′, δ′-ungesättigten Ketonen. 50. Mitteilung über Photoreaktionen

Photochemistry of tricyclic β, γ-γ′, δ′-unsaturated ketones The easily available tricyclic ketone 1 (cf. Scheme 1) with a homotwistane skeleton yielded upon direct irradiation the cyclobutanone derivative 3 by a 1,3-acyl shift. Further irradiation converted 3 into the tricyclic hydrocarbon 4 . However, acetone sensitized irradiation of 1 gave the tetracyclic ketone 5 by an oxa-di-π-methane rearrangement. Again with acetone as a sensitizer the ketone 5 was quantitatively converted to the pentacyclic ketone 6 . The conversion 5 → 6 represents a novel photochemical 1,4-acyl shift. The possible mechanisms are discussed (see Scheme 7). The tricyclic ketone 2 underwent similar types of photoreactions as 1 (Scheme 2). Unlike 5 the tetracyclic ketone 9 did not undergo a photochemical 1,4-acyl shift. The epoxides 10 and 14 derived from the ketones 1 and 2 , respectively, underwent a 1,3-acyl shift upon irradiation followed by decarbonylation, and the oxa-di-π-methane rearrangement (Schemes 3 and 4). The diketone 18 derived from 1 behaved in the same way (Scheme 5). The tetracyclic diketone 21 cyclized very easily to the internal aldol product 22 under the influence of traces of base (Scheme 5). Upon irradiation the γ, δ-unsaturated ketone 24 underwent only the Norrish type I cleavage to yield the aldehyde 25 (Scheme 6).     

Synthetische Verwendung von Epoxynitronen. II. Synthese von Steroid-α-methyliden-γ-lactonen

Synthetic application of epoxynitrones. II. Syntheses of steroidal α-methylidene-γ-lactones This communication describes the application of the epoxynitrone/CF₃SO₃SiR₃ → 1,2-oxazine annelation-reaction [1] to the syntheses of steroidal α-methylidene-γ-lactones from olefines, e.g. 12 → 14a/b → 16a/b → 18a/b → 20 → 22 (Scheme 2).     

σ, π-Isomerisierungen von Monohetero-σ-bishomobenzol-Derivaten. Vorläufige Mitteilung

The cis-oxa- ( 13a-d ) and -aza-σ-bishomobenzene ( 13 e ) derivatives have been synthesized; they are sufficiently stable to be isolated in pure form. On heating, 13a-e are easily isomerized into the π-bishomobenzene analogues 14a-e , the processes 13 a ? 14 a , 13 b ? 14b and 13d ? 14d being reversible. Some kinetic and thermodynamic data for these σ, π,bishomobenzene transformations are presented.     

Über die Natur der Übergangsmetall-Kohlenstoff-σ-Bindung. VIII. Über die Reaktion von 3d-Metallhalogeniden mit Thioanisolyllithium

On the Nature of the Transition Metal Carbon-σ-Bond. VIII. Reaction of 3d-Metal Halides with Thioanisolyl Lithium Reaction of CoBr₂ · 2 THF with PhSCH₂Li/N(CH₂CH₂)₃N (TED) results in the formation of the thiophenolato complex LiCo(SPh)₃ · TED · 3.5 THF (I) with ethylene, propylene, and small amounts of cyclopropane being liberated. The constitution of I follows from the results of the elemental analysis, the effective magnetic moment (μ_eff. = 4.41 B.M.), and the reaction with acids and HgCl₂ to give PhSH and PhSHgCl, respectively. I could also be isolated by comparison synthesis from CoBr₂ · 2 THF and LiSPh/TED. Other 3d-metal halides MX_n · xTHF (M = Ti, V, Mn, Fe, Ni; X = Cl, Br) also react very easily with thioanisolyl lithium to form thiophenolato compounds.     

Synthesis and polymerization of racemic and optically active substituted β-propiolactones. VI. α-Phenyl β-propiolactone

The synthesis and optical resolution of α-phenyl β-amino-ethylpropionate led to the preparation of optically active α-phenyl β-propiolactones (PhPL) of different optical purities. The enantiomeric excess of PhPL was determined using 200 MHz ¹H-NMR spectroscopy, after complexation with tris[3-(trifluoromethyl hydroxymethylene)-d-camphorato]europium III. It was then polymerized, in bulk and in solution, using a potassium acetate/crown ether complex as initiator. The optically active poly(PhPL)s thus obtained are insoluble in most organic solvents, whereas atactic poly(PhPL)s are soluble in CCl₄, CHCl₃, and dichloroethane. Several differences are observed between the physical properties of optically active and atactic poly(PhPL)s. However, atactic poly(PhPL)s are semi-crystalline polymers, similar to poly(α-disubstituted β-propiolactone)s, but in contrast with poly(α-methyl β-propiolactone). Melting (T_f) and glass transition temperatures, as well as enthalpy of fusion (ΔH), vary with the optical purity of the polymers. For example, atactic poly(PhPL) exhibits a T_f = 94°C and ΔH = 9 J/g as compared to T_f = 119°C and ΔH = 37 J/g for a poly(PhPL) having an enatiomeric excess of 50%.     

Nucleophilic Reactions at Tertiary Carbon. Part 3. σ- and π-routes to the 9-decalyl cation

The generation of the 9-decalyl cation by solvolysis of cis- and trans-9-decalyl chloride ( 1 ) has been reinvestigated. The results of product, rate and isomerization studies implicate stereoisomeric ion pairs as intermediates, as in the case of the solvolysis of other stereoisomeric tertiary chlorides (Parts 1 and 2). On the other hand, both symmetrically and unsymmetrically solvated 9-decalyl cations are indicated in the cyclization of 4-(cyclohexen-1-yl)butyl tosylate. No evidence was obtained that conformational isomers of the 9-decalyl cation play a role as product determining intermediates.