Acid-catalysed reactions of 3,5-dialkyl-spiro[2.5]Octa-2,5-dien-4-ones

Acid-catalysed ring opening of the spirodienones ($\text{2a}$) and ($\text{2b}$) using p-toluene-sulphonic acid affords the styrène derivatives ($\text{3a}$) and ($\text{3b}$), while treatment with acetic anhydride/H₂SO₄ affords the furan derivatives ($\text{4a}$) and ($\text{4b}$).     

The chain lengthening of aliphatic aldehydes with the aid of “nucleophilic carbene”

The addition of “nucleophilic carbene” on 1,2,4-triazole bases ($\text{2}$) and aldehydes is decisively influenced by the anion present. 5-(α-Hydroxyalkyl)-1,2,4-triazolium chlorides, formed in the addition reaction of 3-methylthio-1,4-diphenyl-1,2,4-triazolium chloride ($\text{1c}$) with aldehydes, can be easily reduced to 5-alkyl-1,2,4-triazolium iodides ($\text{5}$). Reduction of these with NaBH₄ affords aldehydes by acidic hydrolysis or carboxylic acids by alkaline hydrolysis, the carbon chain of which has been lengthened by one CH₂ group, as compared to the starting aldehyde.     

The replacement of vinylic hydrogen by fluorine

In 3$\text{H}$, 4$\text{H}$-tetrafluoro-3-thiolen and 1$\text{H}$,2$\text{H}$-octafluorocyclohexene, the conversion of -CHCH- into -CHCF- by fluorination over KCoF₄ takes place by saturation to -CHFCHF- followed by dehydrofluorination, and not by direct replacement of a vinylic hydrogen.     

Reaction of bicyclo[3.2.1]octadiene with 4-methyl-1,2,4-triazoline-3,5-dione: competitive dipolar and homo-cycloaddition

The nonconjugated bicyclo[3.2.1]octa-2,6-diene ($\text{1}$) affords with 4-methyl-1,2,4-triazolin-3,5-dione (MTAD) the homo-cycloadduct ($\text{2}$) product and the rearranged urazoles ($\text{3}$) and ($\text{4}$) through dipolar cycloaddition, while ene-reaction and (2+2)-cycloaddition are not observed.     

Nouvelle orientation de la reaction des ylures du phosphore avec les aldehydes

A new reaction of ylids $\text{1}$ with aldehydes is described. C-mono- substituted ylids t-Bu₂P(Cl)=CH-R′ give with aldehydes R“CH=O the phosphine oxydes t-Bu₂P(O)-CH(R′)-CH(Cl)R” stereoselectively; the assymetric ylids t-Bu(R₂N)P(Cl)=CH₂ give a mixture of diastereoisomers.     

A novel ring substitution reaction in a cyclopentadienylruthenium phosphine complex

The reaction between hexafluoroacetone and Ru(PPh₃)₂(π-C₅H₅)[σ-C₂(CO₂Me)₂H] affords a $\text{1}\text{1}$ adduct, containing a coordinated ester group and an intramolecular hydrogen bond; formal insertion of (CF₃)₂CO into a CH bond of the cyclopentadienyl group has also occurred.     

Unusual rearrangement of σ-vinylpalladium complexes into η2-olefin complexes. The structure of (η2-1-triphenylphosphonium-2-carbomethoxyethylene)(triphenylphosphine)iodopalladate

β-Substituted σ-vinylpalladium complexes [Pd(σ-CHCHCOOR)(PPh₃)₂(X)] (I) (X = Cl, I; R = Me, Et) have been obtained by interaction of the E- and Z-β-halogen acrylates with tetrakis(triphenylphosphine)palladium. On heating complexes I rearrange into isomeric η²-olefin-ylidepalladium complexes [$\text{P}$$\text{dCH(COOR)-C}$HPPh₃(PPh₃)(X)] (II). The structure of these com X-ray study of the compound with X = I, R = Me.     

On the question of carbonyl oxide intermediates in the oxygen transfer by furan endoperoxides and bicyclic ozonides: intramolecular trapping experiments

On heating the furan endoperoxide ($\text{2}$) rearranges into the enol ester ($\text{4}$) and the bicyclic ozonide ($\text{3}$) affords instead the rearranged ozonide ($\text{7}$). The process ($\text{2}$) → ($\text{4}$) represents an intramolecular Baeyer-Villiger rearrangement presumably via the dioxirane (D-2), while the process ($\text{3}$) → ($\text{7}$) represents intramolecular trapping of the carbonyl oxide (C-3).     

Stereoselective syntheses of substituted methyl (Z,E,E)-deca-2,7.9-trienoates and substituted methyl (Z,E,E)-undeca-2,8,10-trienoates

Lindlar hydrogenation of substituted methyl ($\text{E}$,$\text{E}$)-deca-7,9-dien-2-ynoates and substituted methyl ($\text{E}$,$\text{E}$)-undeca-8,10-dien-2-ynoates affords selectively the corresponding ($\text{Z}$,$\text{E}$,$\text{E}$)-trienes.     

The reaction of carboalkyxyclopropyltriphenylphosphonium salts with imide anions: a three-step synthesis of ± isoretronecanol

Reaction between carbethoxycyclopropyltriphenylphosphonium tetrafluoborate ($\text{1a}$) and sodium succinimide affords the adduct ($\text{2a}$) which was converted in two additional steps into ± isoretronecanol; some other condensations between ($\text{1a}$) and imide salts are described.     

A facile synthesis of 3,4-homoadamantanediol via the reaction of 1-adamantyl triflate with carbon monoxide

The reaction of 1-adamantyl triflate ($\text{1}$) with carbon monoxide and adamantane catalyzed by triflic acid affords 3-hydroxy-4-homoadamantyl 1-adamantanecarboxylate ($\text{2}$) as a major product, which is easily converted to 3,4-homoadamantanediol ($\text{5}$) — a promising starting material for 3,4-bifunctional homoadamantane derivatives.     

A high yield synthesis of (±)-5,8-dimethoxy-2-α-hydroxyethyl-3,4-dihydronaphthalene,a key intermediate in anthracyclinone synthesis

The dimethoxytetralol ($\text{2}$) gives on Vilsmeier reaction the dihydronaphthaldehyde ($\text{3}$) (yield,92%), which on Grignard reaction with MeMgI affords the title compound ($\text{6}$) (yield,~100%), the reactions constituting a high yield synthesis of this important anthracyclinone intermediate.     

Hydroboration-carbonylation of bisolefinic amines: a facile synthesis of δ-coniceine

Treatment of N-allyl-N-3-butenyl-N-Cbz-amIne ($\text{1}$) with thexyl borane followed by cyanidation affords an azacyclononanone $\text{2}$ in 35% yield which can be transformed into δ-coniceine ($\text{3}$) by catalytic reduction.     

Vacuum flash pyrolysis (VFP) of malonyl peroxides: decarboxylation versus decarbonylation of the intermediary α-lactones

Vacuum Flash Pyrolysis (VFP) at ca. 450–500°C and ca. 0.1–0.3 Torr of the spirocyclic malonyl peroxides ($\text{2a,b}$) affords high yields of allenes ($\text{5a,b}$), while the simple malonyl peroxide ($\text{2c}$) leads to ketone ($\text{4}$), derived respectively from decarboxylation and decarbonylation of the intermediary α-lactones ($\text{3}$).     

Organic transformations via metal silane reagents: syntheses of vinyl ethers from dimethyl ketals and (CO)5MnSi(CH3)3

The reaction of dimethyl ketals with (CO)₅MnSi(CH₃)₃ ($\text{1}$ at 50 °C in CH₃CN affords methyl enol ethers, generally in 75–95% yields.     

Synthesis of homoleptic tris(organo-chelate)iridium(III) complexes by spontaneous ortho-metallation of electronrich olefin-derived N,N′-diarylcarbene ligands and the X-ray structures of fac-[Ir{CN(C6H4Me-p) (CH2)2NC6H3Me-p}3] and mer-Ir{CN(C6H4Me-p)(CH2)2NC6H3Me-p}2 {CN(C6H4Me-p)(CH2)2NC6H4Me-p}Cl (a product of HCl cleavage)

Treatment of [{Ir(COD)(μ-Cl)}₂] with excess of the electron-rich olefin [$\text{CN(Ar)(CH}{}_2\text{)}{}_2\text{N}$Ar]₂ (abbreviated as (L^Ar)₂, Ar = C₆H₄Me-p or C₆H₄OMe-p) affords the ortho-metallated tricycle [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₃], which for Ar = C₆H₄Me-p (Ia) with HCL yields [$\text{Ir(L}{}^{\mathrm{A}}\text{r}$)₂(L^Ar)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir?C(o-aryl) contact (2;52(1) Å) involving the “free” L^Ar which compares with an IrC(o-aryl) distance of 2.09(3) Å in Ia or 2.07(3) Å in the ortho-metallated L^Ar ligand of complex IV.     

Intramolecular silyl migration in the singlet oxygenation of 2-methyl-5-trimethylsilylfuran

Tetraphenylporphyrin-sensitized photooxygenation of 2-methyl-5-trimethylsilylfuran ($\text{4}$) affords quantitatively trimethylsilyl 2-oxo-4-pentenoate ($\text{5}$), presumably via intramolecular Baeyer-Villiger rearrangement of the intermediary dioxirane ($\text{3a}$).     

On the steric course of baker's yeast mediated reduction of alkyl 4-azido- and 4-bromo-3-oxobutyrate. Synthesis of (R)- and (S)-carnitin

Baker's yeast reduction of ethyl 4-azido- and 4-bromo-3-oxobutyrate affords (3$\text{R}$) (8) and (3$\text{S}$) (2), respectively, in high optical purity.     

Hydration of the 2-monoanil of 1,3-diphenylpropane-1,2,3-trione. Revised structure of the hydration product.

The base-catalyzed hydration of anil $\text{1}$ affords O-benzoylmandelanilide ($\text{7}$) rather than hydroxylamine $\text{2}$ as was previously reported.     

Diazothenes: evidence for their production by way of a Wittig reaction.

Base-promoted reaction of dimethyl diazomethylphosphonate ($\text{1}$) with dialkyl and cyclic ketones affords species having the chemical properties associated with vinylidenes ($\text{3}$) or their equivalents. Data are presented showing that diazoethenes ($\text{2}$) are unexpectedly unstable, losing nitrogen even at ?78°C to give the corresponding carbenes or carbenoids.