Some 1,3-dipolar cycloaddition reactions of perfluoro-(2-azido-4-isopropylpyridine) and 2-azido-3,5,6-trifluoro-4-methoxypyridine

In continuation with studies on perfluorinated aryl [1] and hetaryl [2] azides some 1,3-dipolar cycloaddition reactions of perfluoro-(2-azido-4-isopropylpyridine) are summarized in Scheme 1. The azide reacts with styrene under forcing thermal conditions to give a mixture of perfluoro-(2-amino-4-isopropylpyridine) and benzaldehyde involving a more unusal type of cleavage of the triazoline formed initially [2]. Perfluoro-(2-azido-4-isopropyl-pyridine) does not react with cyclopentene or cyclohexene upto 110 °C but when the reaction is carried out at the decomposition temperature of the azide i.e. 160 °C, a mixture of the amino compound and the corresponding cyclic ketone is obtained. It is believed that at 160 °C the reaction still proceeds $\text{via}$ 1,3-cycloaddition because no evidence of nitrene formation was found when the azide was decomposed thermally or photochemically in the presence of conventional nitrene traps e.g. dimethyl sulphoxide, cyclohexane etc. [2] and only polymeric material was obtained. Perfluoro-(2-azido-4-isopropylpridine) reacts smoothly with norbornene at room temperature with evolution of nitrogen and only the products of decomposition of initially formed triazoline are obtained.     

Reactions of in-situ generated acyllithium reagents with carbon disulfide and carbonyl sulfide

In-situ generated (at ?110°C to ?135°C) acyllithium reagents, RC(O)Li (R = $\text{t}$-Bu, $\text{n}$-Bu), react with CS₂, to give [RCOS]Li with loss of Cs. On the other hand, COS reacts to give [RC(O)COS]Li.     

1,6-dithia-spiro[4.4]nonadiene aus 2-thiazolin-5-thionen

4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione ($\text{4}$) reacts with 2,3-diphenylcyclopropenone ($\text{2a}$) at 145°C and with benzonitrilio-2-propanide ($\text{6}$) at room temperature to yield the 1,6-dithia-spiro[4.4]nonadienes $\text{5}$ and $\text{7}$, respectively.     

Studies on organophosphorus compounds XLVII preparation of thiated synthons of amides,lactams and imides by use of some new p,s-containing reagents

The thionation properties of 2,4-bismethylthio-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{1}$, 2,4-bis(4-phen-oxyphenyl)-1,3,2,4-dithiaphosphetan is that $\text{2}$, $\text{3}$ and thionate most amides and lactams In THF at room temperature (reaction time 5 min) to give the corresponding thionated compounds. Imides are easily thionated by $\text{2}$, $\text{3}$ and $\text{4}$ In DME at 60 °C. The reactions of $\text{1}$ with amides, imides and most lactams are run at 60°C to give good yields of the corresponding thionated compounds.     

Temperature- and substituent-dependence in the photosensitized oxygenation of N,N-disubstituted hydrazones

Methylene blue-sensitized photooxidation of N,N-disubstituted hydrazones $\text{1a-f}$ gave various products $\text{2-9}$, depending on the reaction temperature and N-substituents. The major reaction modes from the photo-oxidation of N,N-diphenylhydrazones were α-oxidation at room temperature and C=N cleavage at ?78 °C in contrast to C=N cleavage as an only reaction mode for the photooxidation of N,N-dimethylhydrazones at either room temperature or ?78 °C.     

Einschiebung von inaminen in metall—carbenkohlenstoff-bindungen

Pentacarbonyl[methoxy(methyl)carbene]chromium(0) and pentacarbonyl[methoxy(phenyl)carbene]chromium(0) react in hexane at room temperature with diethylaminoethyne and l-diethylamino-1-propyne to give $\text{1}\text{1}$ compounds. These are identified as insertion products of the alkyne entity into the metal—carbene bond by spectroscopic methods.     

Thionin oxide as a Possible Intermediate on Periodate Oxidation of 9-Thiabicyclo[6.1.0]nona-2,4,6-triene

9-Thiabicyclo[6.1.0]nona-2,4,6-triene was oxidized at ?15 to ?20°C with sodium periodate in a methanol-water medium. The major isolated product was established as $\text{cis}$3a,7a-dihydrobenzo[b]thiophene-$\text{cis}$-1-oxide, which is best explained as arising from intramolecular cycloaddition of a thionin oxide intermediate.     

Substituent influence on the indolization with pcl3 of some o,m,p-substituted phenylhydrazones

The indolization of deoxybenzoin $\text{o}$,$\text{m}$,$\text{p}$ (Me, MeO, Cl), $\text{p}$-NO₂ and $\text{m}$-EtO-phenylhydrazones (1) by the above reaction has been examined. All the reactions are carried out at room temperature and high yields of the corresponding indoles (2) are obtained even when -NO₂ substituent is present. In this case longer reaction time is necessary. Alkoxyphenylhydrazones give the corresponding indoles (2) in high yields without showing collateral reactions which indeed are present in several Fischer routes on these derivatives. $\text{m}$-Substituted phenylhydrazones (1) give a mixture of 4- and 6-substituted indoles in which the 6-isomer is always prevalent, a feature not inherent in the Fischer reactions. The regioselectivity is enhanced by the substituent steric hindrance increasing. The reaction can be also carried out at 0°C with a further improvement of its regioselectivity.     

4-Acetoxytricyclo[4.1.0.02,7]Hept-4-en-3-one; synthesis and novel bond reorganization of a valence isomer of 2-acetoxytropone

4-Acetoxytricyclo[4.1.0.0^2,7]hept-4-en-3-one ($\text{3}$), a valence isomer of 2-acetoxytropone, was synthesized. Upon heating in pyridine at 150°C, $\text{3}$ rearranged into 1-acetoxybicyclo[3.2.0]hepta-3,6-dien-2-one ($\text{9}$); the mechanism of which was examined by means of deuterium labeling experiments.     

Ring cleavage rearrangement of cyclobutylmethylboranes

Boranes derived from hydroboration of methylenecyclobutane with borane/THF, 9-borabicyclo[3.3.1]nonane, and borane-methyl sulfide rearranged on heating in situ at 100–160°C to open chain structures. Products after oxidation were the unrearranged cyclobutylmethanol, and 4-penten-1-ol, 1,4-pentanediol and 1,5-pentanediol. The unsaturated alcohol was the major product in reactions with a stoichiometric ratio of alkene to BH bonds, and the diols were formed with excess borane. With borane-methyl sulfide as hydroborating reagent, the rate of rearrangement at 100°C in triglyme was not significantly dependent upon the initial alkene/borane ratio $\text{3}\text{1}$ or $\text{1.15}\text{1}$ or the presence of excess methyl sulfide. However, an equivalent amount of pyridine prevented rearrangement. Rearrangement in THF using borane/THF also occurred at comparable rates in the presence and absence of excess borane. Little or no isomerization of the boron function into the cyclobutane ring was observed. Results are interpreted on the basis of a concerted four-center mechanism which requires a vacant boron orbital.     

A carbene route to dehydro[m.n.]paracyclophanes

Pyrolysis of the [2.2]paracyclophanyl diazomethane (1) at 270–300°C led to the product of carbon-hydrogen insertion (2) and $\text{cis}$-1,2-dehydro[3.2]paracyclophane (3).     

Flash vacuum pyrolysis of 1-propynoylpyrazoles: a new precursor of tricarbon monoxide

Pyrolysis of 3,5-dimethyl-1-propynoylpyrazole (1) at 640°C/0.1 torr gives 2-methyl-1$\text{H}$-pyrazolo[2,3-a]pyridin-5-one (3) with inversion of the propynoyl chain. 1-Ethynylpyrazole and tricarbon monoxide have been identified in pyrolysates formed at 700–1000°C/0.01–0.1 torr from the parent 1-propynoylpyrazole (4).     

Some reactions of 1,2,3,4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene: Thermolysis and attack by methoxide ion and by bistrifluoromethyl nitroxide

1,2,3,4,7,7-Hexafluorobicyclo[2,2,1]hepta-2,5-diene gave 1,2,3,4-tetrafluorebenzene in at least 73% yield when heated to 450°C in a sealed tube; the CF₂ bridge appeared, in part, as octafluorocyclobutane. Nucleophilic attack by sodium methoxide- methanol on the diene occurred exclusively at the CFCF bond, causing the formation of 1,2,4,7,7-pentafluoro-3-methoxybicyclo- [2,2,1]hepta-2,5-diene and a 1,4,5,6,7,7-hexafluoro-5-methoxybicyclo [2,2,1]hept-2-ene thought, on the basis of ¹⁹F nmr data, to be the 6-$\text{endo}$-F,5-$\text{exo}$-MeO isomer. Radical attack on 1,2,3,- 4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene by bistrifluoromethyl nitroxide took place at both olefinic sites, with a $\text{ca}$. 10:1 preference for the CFCF linkage; all three geometrical isomers of 5,6-bis(bistrifluoromethylamino-oxy)-1,4,5,6,7,7- hexafluorobicyclo[2,2,1]hept-2-ene were formed.     

Studies in azide chemistry. Part 12. One-pot conversion of 4-azidotetrafluoropyridine to 1,3,4-trifluoro-7,9-dimethyl-11H-pyrido[4,3-c]benzo[1,2]diazepine

Thermolysis of 4-azidotetrafluoropyridine in the presence of an excess of mesidine at 170 °C yields tetrafluoro-4-(2,4,6-trimethylphenylazo)- pyridine, which undergoes intramolecular dehydrofluorination $\text{in situ}$ to provide 1,3,4-trifluoro-7,9-dimethyl-11$\text{H}$-pyrido[4,3-$\text{c}$]benzo[1,2]diazepine.     

Evidence for single electron transfer in metal-halogen exchange. The reaction of organolithium compounds with alkyl halides.

The reaction of $\text{t}$-BuLi with cyclizable 1° and 2° alkyl halide radical probes at low temperature produced stab]e cyclized and uncyclized organolithium products as well as cyclized hydrocarbons which clearly indicate the presence of radical intermediates during the course of these reactions.     

Synthesis and structure of an infinite-chain form of ZrI2 (α)

The synthesis of a second polymorph of ZrI₂ has been achieved by a transport reaction between ZrI₄ and zirconium metal under a $\text{750}\text{850}\text{°}\text{C}$ gradient in a sealed tantalum tube. The black lath-like crystals produced in the 775°C region occur in space group $\text{P2}{}_1\text{m}$ with a = 6.821(2) Å, b = 3.741(1) Å, c = 14.937(3) Å, β = 95.66(3)°, Z = 4. A total of 669 independent reflections with 2θ ≤ 50° and I > 3σ(I) were measured at room temperature on a four-circle automated diffractometer with monochromatized MoKα radiation and were corrected for absorption (μ = 190 cm^?1). The structure was solved by direct methods and full-matrix least-squares refinement of all atoms with anisotropic thermal parameters to give final residuals R = 0.064 and R_w = 0.079. This phase is isoelectronic and isostructural with β-MoTe₂, a distorted CdI₂-type structure in which the zirconium atoms are displaced 0.440 Å from the octahedral centers along a to form infinite zigzag metal chains (d_ZrZr = 3.182(3) Å) parallel to b. The phase is a diamagnetic semiconductor at room temperature (E_g ～ 0.1 eV).     

Comparative reactions between aziridines and F2, COF2, CF3OF

In CFCl₃, aziridines $\text{I}$ react with F₂(6 %/N₂,  20°C), COF₂ (20 %/N₂,  40°C) and CF₃OF [1] (20 %/N₂,  40°C).Substitution products are obtained : l-(aziridine)carbonyl fluorides $\text{II}$ and l-Fluoroaziridines $\text{III}$

In (Et)₂O, aziridines $\text{I}$ react with COF₂ (20 %/N₂, 10°C) and we have the carbonyl fluorides $\text{IV}$.

Products IV can be thermally decomposed into β fluoro isocyanates.In CFCl₃, N substituted aziridines $\text{V}$ react with F₂(6%/N₂, 20°C) and with CF₃OF [2] (20%/N₂, 40°C). No reaction is observed with COF₂in our conditions (5% to 25%/N₂, 80°C to + 40°C).Addition products are obtained : N Fluoro amines β fluorinated $\text{VI}$, N Fluoro and NN difluoro amines β trifluoro methoxylated $\text{VII}$ and $\text{VIII}$.

with R = SO₂Ø, COØNO₂, Cl.     

The photochemical reactions of α,β,γ,δ -unsaturated diazo compounds at low temperature

The α,β:γ,δ-unsaturated tosylhydrazone lithium salts (4) undergo photolysis at ?60°C to give vinylcyclopropenes (10) and [l,2]diazeto[l,4-a] pyrroles (11) and/or (12). The formation of (11, X=H) establishes the intermediacy of (8, X=H) in the formation of the 3$\text{H}$-1,2-diazepine (9). The diazoalkene (5, X=Me) showed opposite electrocyclisation periselectivity to its thermal cyclisation and gave (11, X=Me) $\text{via}$ (8, X=Me), rather than the pyrazoles (2) and (3).     

[1,5] Sigmatropic shifts in a 1,4-diphospholylbenzene

The central phenylene ring of 1,4-bis(3,4-dimethylphosphol-1-yl)benzene undergoes [1,5] shifts around both phospholyl rings above 150°C to give 1,4-bis(3,4-dimethyl-5H-phosphol-2-yl)benzene, which can be trapped by tolane, [CpFe(CO)₂]₂, or Mn₂ (CO)₁₀ to yield the corresponding bis-1-phosphanor-bornadiene, bis-phosphaferrocene, or bis-phosphacymantrene respectively.     

Studies on amino acids and peptides-III. 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide,LR, as a new racemization free coupling reagent in peptide synthesis

The easily accessible 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{LR}$, has been reacted with salts of N-protected amino acids $\text{1}$ (Z-Gly-OH, Boc-Gly-OH, Boc-S-Ser(Bzl)-OH, Boc-S-Tyr(Bzl)-OH, Z-S-Arg(Z₂)-OH, and Z-S-Pro-OH), at room temperature in CH₂Cl₂ to give the intermediates $\text{2}$, mixed anhydrides. When $\text{2}$ is treated with two moles of a base and one mole of the salt of an amino acid ester $\text{3}$ (TosOH·H-Gly-OBzl, HCl·H-Gly-OBzl, HCl·H-Gly-OEt, and HCl·H-S-Phe-OtBu) at 0°C, the expected peptide $\text{4}$ is isolated in high yields. LR is also found to be a useful reagent in a fragment coupling between Z-Gly-S-Ala-OH and TosOH·H-S-Leu-OBzl). This tripeptide was tested by means of HPLC (deprotection and amino acid analysis according to Izumiya was not necessary), and no epimerization (<0.7 %) was observed.