Acyl Iodides in Organic Synthesis: II. Reactions with Acyclic and Cyclic Ethers

Reaction of acyl iodides RCOI (R = Me, Ph) was studied with acyclic and cyclic ethers (Et₂O, MeCHCH₂(O), ClCH₂CHCH₂(O), THF, O(CH₂CH₂)₂O, EtOCH₂CH₂OH, EtOCH = CH₂, PhOEt]. The reaction occurred with the rupture of one or two CO bonds furnishing the corresponding iodides and esters.     

A problem related to the arithmetic of probability measures on the sphere

The class I_o is described in the convolution semigroup of probability measure on the sphere in Rⁿ which are invariant under rotations about a fixed axis; it is established that the indecomposable measures form a dense set in the topology of weak convergence.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 87, pp. 143–158, 1979.I am deeply grateful to Professor I. V. Ostrovskii for the continual attention he has paid to my work.     

Porphyrin-phthalocyanine/pyridylfullerene supramolecular assemblies

The synthesis and photophysical properties of several porphyrin (P)-phthalocyanine (Pc) conjugates (P-Pc; 1-3) are described, in which the phthalocyanines are directly linked to the β-pyrrolic position of a meso-tetraphenylporphyrin. Photoinduced energy- and electron-transfer processes were studied through the preparation of H(2)P-ZnPc, ZnP-ZnPc, and PdP-ZnPc conjugates, and their assembly through metal coordination with two different pyridylfulleropyrrolidines (4 and 5). The resulting electron-donor-acceptor hybrids, which were formed by axial coordination of compounds 4 and 5 with the corresponding phthalocyanines, mimicked the fundamental processes of photosynthesis; that is, light harvesting, the transduction of excited-state energy, and unidirectional electron transfer. In particular, photophysical studies confirmed that intramolecular energy-transfer resulted from the S(2) excited state as well as from the S(1) excited state of the porphyrins to the energetically lower-lying phthalocyanines, followed by an intramolecular charge-transfer to yield P-Pc(.+)?C(60)(.-). This unique sequence of processes opens the way for solar-energy-conversion processes.     

Acyl iodides in organic synthesis: VIII. Reactions with amino acids

Reactions of acyl iodides RCOI (R=Me, Ph) with glycine, β-alanine, and γ-aminobutyric acid were investigated. The reaction proceeded easily at room temperature without solvent involving both functional groups H₂N and COOH. The prevalence of one of the reaction directions depends on the acidity of the amino acid. The more acidic glycine (pК_a 2.4) reacts with RCOI affording mainly N-acylated product, whereas β-alanine (pК _a 3.60) and especially γ-aminobutyric acid (pК_a 4.06) are predominantly involved into exchange iodination furnishing the corresponding aminoacyl iodides.     

Synthesis and photophysical properties of fullerene-phthalocyanine-porphyrin triads and pentads

The synthesis and photophysical properties of several fullerene-phthalocyanine-porphyrin triads (1-3) and pentads (4-6) are described. The three photoactive moieties were covalently connected in an one-step synthesis through 1,3-dipolar cycloaddition to C(60) of the corresponding azomethine ylides generated in situ by condensation reaction of a substituted N-porphyrinylmethylglycine derivative and an appropriated formyl phthalocyanine or a diformyl phthalocyanine derivative, respectively. ZnP-C(60)-ZnPc (3), (ZnP)(2)-ZnPc-(C(60))(2) (6), and (H(2)P)(2)-ZnPc-(C(60))(2) (5) give rise upon excitation of their ZnP or H(2)P components to a sequence of energy and charge-transfer reactions with, however, fundamentally different outcomes. With (ZnP)(2)-ZnPc-(C(60))(2) (6) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP(.+))-ZnPc-(C(60)(.-))(C(60)). The lower singlet excited state energy of H(2)P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H(2)P)(2)-ZnPc-(C(60))(2) (5) not competitive. Instead, a transduction of singlet excited state energy prevails to form the ZnPc singlet excited state. This triggers then an intramolecular charge transfer reaction to form exclusively (H(2)P)(2)-ZnPc(.+)-(C(60)(.-))(C(60)). A similar sequence is found for ZnP-C(60)-ZnPc (3).     

Taming C60 fullerene: tuning intramolecular photoinduced electron transfer process with subphthalocyanines

Two subphthalocyanine–C₆₀ conjugates have been prepared by means of the 1,3-dipolar cycloaddition reaction of (perfluoro) or hexa(pentylsulfonyl) electron deficient subphthalocyanines to C₆₀. Comprehensive assays regarding the electronic features – in the ground and excited state – of the resulting conjugates revealed energy and electron transfer processes upon photoexcitation. Most important is the unambiguous evidence – in terms of time-resolved spectroscopy – of an ultrafast oxidative electron transfer evolving from C₆₀ to the photoexcited subphthalocyanines. This is, to the best of our knowledge, the first case of an intramolecular oxidation of C₆₀ within electron donor–acceptor conjugates by means of only photoexcitation.     

A metal–organic framework/polymer derived catalyst containing single-atom nickel species for electrocatalysis

While metal–organic frameworks (MOF) alone offer a wide range of structural tunability, the formation of composites, through the introduction of other non-native species, like polymers, can further broaden their structure/property spectrum. Here we demonstrate that a polymer, placed inside the MOF pores, can support the collapsible MOF and help inhibit the aggregation of nickel during pyrolysis; this leads to the formation of single atom nickel species in the resulting nitrogen doped carbons, and dramatically improves the activity, CO selectivity and stability in electrochemical CO₂ reduction reaction. Considering the vast number of multifarious MOFs and polymers to choose from, we believe this strategy can open up more possibilities in the field of catalyst design, and further contribute to the already expansive set of MOF applications.

A metal–organic framework/polymer derived catalyst containing single-atom nickel species shows good performance for electroreduction of CO₂ to CO.     

Acyl Iodides in Organic Synthesis: IV. Reaction of Acetyl Iodide with Carboxylic Acids

In contrast to acyl chlorides, reactions of acetyl iodide with monocarboxylic acids follow the exchange pattern to give the corresponding acyl iodides and acetic acid. The reaction attracts interest from the preparative viewpoint as a simple and convenient route to acyl iodides. Acetyl iodide reacts with phthalic acid, yielding acetic acid and phthalic anhydride, while the reaction of acetyl iodide with oxalic acid leads to formation of acetic acid, carbon(II) oxide, and molecular iodine.     

Acyl iodides in organic synthesis: X. Reactions with triorganylsilanes and triphenylgermane

Reaction of acyl iodides RCOI (R = Me, Ph) with triorganylsilanes R′₂R″SiH in toluene gives 50–60% of the corresponding triorganyliodosilanes R′₂R″SiI. Triethylsilane reacts with the same acyl iodides under solvent-free conditions to afford the corresponding aldehyde and triethyliodosilane as primary products. Triethyliodosilane undergoes subsequent transformations into hexaethyldisiloxane and triethyl(acyloxy)silane Et₃SiOCOR (R = Me, Ph). Reactions of acyl iodides RCOI (R = Me, Ph) with triphenylgermane in the absence of a solvent lead to formation of iodo(triphenyl)germane in more than 90% yield.