Ozonolysis of Alkenes and Study of Reactions of Polyfunctional Compounds: LXIII. A New Procedure for Direct Reduction of 1-Methylcycloalkene Ozonolysis Products to Hydroxyketones

A procedure was proposed for direct reduction of peroxide products resulting from ozonolysis of 1-methylcycloalkenes to the corresponding hydroxyketones by the action of sodium triacetoxohydridoborate.     

Ozonolysis of Alkenes and Study of Reactions of Polyfunctional Compounds: LXVI.2* Ozonolysis and Hydrogenation of Diacetonides of 24,25- and 25,26-Anhydro-20-hydroxyecdysones. Synthesis of Ponasterone A

Ozonolysis of 2,3:20,22-diacetonides of 24.25-and 25,26-anhydro-20-hydroxyecdysones afforded the corresponding -carbonyl derivatives. The hydrogenation of the mentioned dehydration products of 20-hydroxyecdysone acetonide yielded diacetonide of ponasterone A that provided ponasterone A and its 29,22-acetonide at hydrolysis.     

Ozonolysis of Alkenes and Study of Reactions of Polyfunctional Compounds: LXVII. Synthesis of 27,27,27-Trifluoro-20-hydroxyecdysone Acetonides from 24,25- and 25,26-Anhydro-20-hydroxyecdysone Derivatives via Ozonolysis and Trifluoromethylation

Ozonolysis of 24,25/25,26-anhydro derivatives of 20-hydroxy-2,3:20,22-di-O-isopropylidene-ecdysone and 2,3-di-O-acetyl-20-hydroxy-20,22-O-isopropylideneecdysone, followed by trifluoromethylation of the corresponding 25-oxo derivatives afforded 2,3:20,22-di-O-isopropylidene- and 20,22-O-isopropylidene-27,27, 27-trifluoro-20-hydroxyecdysones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 387–395.Original Russian Text Copyright © 2005 by Odinokov, Savchenko, Afon’kina, Khalilov.For communication LXVI, see [1].     

Reissert Compound Studies. LXI. Preparation and Reactions of Quinazoline Di-Reissert Compounds

Various di-Reissert compounds and analogs were prepared from quinazoline by use of trimethylsilyl cyanide together with a catalytic amount of anhydrous aluminum chloride. Reactions of these quinazoline di-Reissert compounds are reported.     

Synthesis of Vinca Alkaloids and Related Compounds. LXV. Preparation of 7-Methoxytryptamine

7-Methoxytryptamine (6a) was prepared from cheap and easily available starting materials by using the Abramovitch-Shapiro method.     

Ozonolysis of naphthoquinones—I Ozonolysis of 1:4-naphthoquinone in chloroform

During ozonisation of 1:4-naphthoquinone in chloroform at −5 to −8° about 70 per cent undergoes anomalous ozonolysis forming phenylglyoxal-o-carboxylic acid and probably carbon monoxide. The remaining 30 per cent forms a normal ozonide which rearranges to a mixed anhydride of formic acid and phenylglyoxal-o-carboxylic acid. Sodium iodide reduction of the normal ozonide produces o-phenylenediglycolaldehyde. An intramolecular benzoin condensation of this substance is discussed.     

Transannular Cyclizations in Caged Bislactones: Synthesis of Polyfunctional Cyclopentanes and Oxa-Cage Compounds

The reactions of dilactones based on bicycl[2.2.1] heptane and [2.2.2]octane systems with Grignard reagents and LiA1H₄ furnished polyfunctional cyclopentanes and oxa-cage compounds resulting from extensive transannular interactions.     

Isomerization and Decomposition of a Criegee Intermediate in the Ozonolysis of Alkenes: Dynamics Using a Multireference Potential

The isomerization and decomposition dynamics of the simplest Criegee intermediate CH₂OO have been studied by classical trajectory simulations using the multireference ab initio MR‐PT2 potential on the fly. A new, accelerated algorithm for dynamics with MR‐PT2 was used. For an initial temperature of 300 K, starting from the transition state from CH₂OO→CH₂O₂ , the system reaches the dioxirane structure in around 50 fs, then isomerizes to formic acid (in ca. 2800 fs), and decomposes into CO+H₂O at around 2900 fs. The contributions of different configurations to the multiconfigurational total electronic wave function vary dramatically along the trajectory, with diradical contributions being important for transition states corresponding to H‐atom transfers, while being only moderately significant for CH₂OO. The implications for reactions of Criegee intermediates are discussed.     

Ozonolysis of a Series of Methylated Alkenes: Reaction Rate Coefficients and Gas‐Phase Products

The gas‐phase ozonolysis of three methylated alkenes, i.e., trans‐2,2‐dimethyl‐3‐hexene (22dM3H), trans‐2,5‐dimethyl‐3‐hexene (25dM3H), and 4‐methyl‐1‐pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas‐phase product concentrations were determined via online sampling either on three‐bed adsorbent cartridges followed by thermodesorption and GC/FID‐MS analysis or on 2,4‐dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10^?17 for 22dM3H and (2.71 ± 0.26) × 10^?17 for 25dM3H, both in cm³ molecule^?1 s^?1 units, have been obtained under pseudo–first‐order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor.     

One-Pot,Two-Step Direct Conversion of Alkenes to Amines Through Tandem Ozonolysis and Ammonia-Borane in Water

An efficient, one-pot, two-step reductive amination of alkenes through tandem ozonolysis using ammonia-borane as a reducing agent is described. The reaction has been carried out in water. This is a highly efficient and mild procedure that is applicable to a wide variety of amine substrates. In particular, this is the first successful manifestation that this type of reaction can be carried out in water with ammonia-borane.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Bond-Forming Initiation in Spontaneous Addition and Polymerization Reactions of Alkenes

Spontaneous addition and polymerization reactions of alkenes of different electron-densities result in a wide variety of small organic molecules and high polymers. Tetramethylenes are proposed as key intermediates, i.e. resonance hybrids of 1,4-diradical and zwitterionic limiting structures. Their character is determined by the substituents at the terminals: Zwitterionic character is favored by strong donors, such as alkoxy and dialkylamino groups, at the carbenium center and strong acceptor group such as diesters and cyano-esters, at the acceptor end, and aryl and vinyl groups as donors. Zwitterionic tetramethylenes initiate ionic homopolymerization, while diradical tetramethylenes initiate alternating copolymerization, thus providing an extremely sensitive technique for the detection and characterization of these intermediates. The effects of the donor and acceptor substituents can be arranged as an “Organic Chemist's Periodic Table”, wherein the areas of mechanistic change clearly emerge and which provides predictive capability.—This unifying concept of bondforming initiation is extended to spontaneous addition and polymerization reactions of heteroatom acceptor molecules and 7,7,8,8-tetrasubstituted quinodimethanes and of compounds possessing labile σ-bonds, such as halogens and peroxides. Radical-ion pairs, charge-transfer complexes and adventitious impurities are excluded as significant initiators.     

RCTA Techniques Used in Studies of Solid State Reactions in Inorganic Compounds

The Reaction Controlled Thermal Analysis techniques, RCTA, are very useful both in thermogravimetric and dilatometric studies. In the present paper this big family of techniques is divided into three main classes: Quasi-Isothermal techniques (QIA); Controlled Reaction Rate Thermal Analysis (CRTA) and Reaction (Event) Controlled Heating Rate Adaption. After a short presentation of these techniques and the general advantages of RCTA, two examples of kinetic studies on thermal decomposition of Ba- and Ce oxalates by using Stepwise Isothermal Analysis, SIA, introduced by the author is presented and discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radiation Chemical Studies of Protein Reactions: Effect of Sulfur-Containing Compounds on Optical Rotation

Thiourea, thioglycol, and β, β′-thiodiglycolic acid were found to protect against changes in the internal relationships of the atoms in the protein molecule from radiation damage. The optical rotation behavior closely resembles that of amino acid which shows a similar dependence on concentration.