A short and efficient synthesis of 1,5-anhydro-d-glucitol 6-phosphate

The important d-glucose and d-glucose 6-phosphate analogues 1,5-anhydro-d-glucitol and 1,5-anhydro-d-glucitol 6-phosphate were prepared from methyl-d-glucoside in high yield and purity. Protecting of the hydroxyl groups as their allyl ether followed by reductive cleavage of the glycosidic linkage with triethylsilane formed the protected anhydroglucitol. No ring rearrangement or ring contraction was observed during the reduction step. Using the PdCl₂-CuCl₂-activated charcoal system, the allyl ether bond was cleaved with a low loading of the catalyst (0.0025 equiv per allyl group). 1,5-Anhydro-d-glucitol 6-phosphate was prepared by the phosphylation of 1,5-anhydro-d-glucitol.     

Copper‐Catalyzed Borylative Allyl–Allyl Coupling Reaction

Borylative allyl–allyl coupling using allenes, bis(pinacolato)diboron, and allyl phosphates has been developed in the presence of a copper catalyst bearing an N‐heterocyclic carbene ligand. The reaction affords boryl‐substituted 1,5‐diene derivatives in good to high yields with high regioselectivity and Z selectivity.     

Ketenimines from Isocyanides and Allyl Carbonates: Palladium‐Catalyzed Synthesis of β,γ‐Unsaturated Amides and Tetrazoles

The reaction of allyl ethyl carbonates with isocyanides in the presence of a catalytic amount of Pd(OAc)₂ provided ketenimines through β‐hydride elimination of the allyl imidoylpalladium intermediates. The insertion of the isocyanide into the π‐allyl Pd complex proceeded via an unusual η¹‐allyl Pd species. The resulting ketenimines were hydrolyzed to β,γ‐unsaturated carboxamides during purification by flash column chromatography on silica gel or converted in situ into 1,5‐disubstituted tetrazoles by [3+2] cycloaddition with hydrazoic acid or trimethylsilyl azide.     

Catalytic intermolecular allyl-allyl cross-couplings between alcohols and boronates

We developed catalytic intermolecular C(sp(3))-C(sp(3)) cross-couplings between various allyl alcohols and allyl boronates, which proceeded smoothly in the presence of nickel(0) under mild conditions to form 1,5-dienes with excellent linear- and γ-selectivity; the use of boronates proved to be crucial in terms of reactivity.     

Synthetic applications of metal-stabilized carbenium ions.IV. preparation of 1,5-ene-ynes via coupling of [(propargyl) dicobalt hexacarbonyl] cations with allyl silanes.

A highly selective and flexible route to 1,5-ene-ynes is provided by the reactions of [(propargyl) dicobalt hexacarbonyl] cations with allyl silanes.     

TBAF‐Mediated Dimerization Reaction of β,γ‐Unsaturated Arylketones

A simple and high‐yield method for the synthesis of several 1,5‐diaryl‐1,5‐dicarbonyl compounds has been established starting from TBAF‐mediated isomerization and dimerization reaction of β,γ‐unsaturated arylketones (allyl arylketones) with mono‐, di‐, and tri‐methoxy groups, which is derived from allylation of commercially available different benzaldehydes and followed by oxidation of the resulting secondary alcohols.     

Complexes de l'iridium avec le cyclooctadiène-1,5 IV. Le di-υ-chloro-bis(π-cylooctadiène-1,5)-bis(π-ether diallylique)-diiridium

Di-μ-chlorobis(π-cycloocta-1,5-diene)diiridium, (I), reacts with allyl alcohol to give a complex, (II), of (I) and diallyl ether and byproducts: propene, propanal and diallyl ether. The same complex is readily obtained by direct reaction of (I) and diallyl ether. Some physicochemical properties (II) are described (IR spectra, stability, reactivity, etc.). Its structure is discussed, and a mechanism for the transformation of allyl alcohol during the reaction is given.     

Triflimide-catalyzed allyl-allyl cross-coupling: a metal-free allylic alkylation

A highly efficient metal-free intermolecular C(sp3)-C(sp3) allyl-allyl cross-coupling protocol between allyl acetates and allyltrimethylsilanes, which proceeded smoothly in the presence of catalytic triflimide to form 1,5-dienes with good to excellent regioselectivity, has been developed.     

Telomerization Studies with Allyl Ethene Sulfonate and Allyl Allyl Sulfonate

Telomerization of allyl ethene sulfonate (AES) in the presence of butyl mercaptan yielded a mixture of two products: the first was a five-membered ring sultone containing a sulfide group and the second a five-membered ring sulfonium salt formed by reaction of the sultone of the Just product with its own sulfide function. If cyclotelomerizations and cyclopolymerizations give the same ring structures, these results indicate that the cyclic units in poly-AES are five-membered rings. Telomerization of allyl allyl sulfonate (AAS) in the presence of butyl mercaptan yielded a mixture of two products formed by addition of butyl mercaptan to one of the two allyl functions. Telomerization of AAS in bromotrichloromethane yielded a small amount of 1,5-hexachIoro-3-bromopentane formed via fission of an oxygen-carbon bond, and a rearranged adduct. The rearrangement of the allyl group to a propenyl group in the case of AAS was not observed when allyl ethane sulfonate or propyl allyl sulfonate were telomerized under the same conditions. Therefore a mechanism is proposed in which the rearrangement of the allyl double bond in AAS is due to the presence of a second double bond in the same molecule. This observation also indicates that poly-AAS might have a more complicated structure than expected from a simple cyclopolymerization mechanism.     

Insect pheromones and their analogues XXIV. Synthesis of long-chain 1,5-dimethyl-branched pheromones from geranyl acetate

Schemes for the synthesis of long-chain 1,5-dimethyl-branched pheromones (7,11-dimethyloctadecane, 15,19-dimethyltritriacontane, and 2-acetoxy-3,7-dimethylpentadecane) from the product of the allyl oxidation of geranyl acetate (8-acetoxy-2,6-dimethylocta-2E,6E-dien-1-ol) have been developed.     

Microwave-accelerated Claisen rearrangements of allyl tetronates and tetramates

[3,3]-Sigmatropic rearrangements of allyl tetronates and allyl tetramates to give 3-allyltetronic or -tetramic acids, respectively, proceed within 20-60 min under microwave irradiation (300 W, 130-190 °C). Consecutive (homo)sigmatropic [1,5] H-shifts such as oxa-ene reactions are promoted less effectively, which allows the isolation of Claisen intermediates of sigmatropic domino sequences, in contrast to conventional heating.     

Nickel-catalyzed allylation of allyl carbonates with homoallyl alcohols via retro-allylation providing 1,5-hexadienes

A highly efficient and mild method for the synthesis of 1,5-hexadienes, nickel-catalyzed reactions of Boc-protected allyl alcohols with homoallyl alcohols, has been developed. Nickel-mediated retro-allylation allows for the use of homoallyl alcohols as allylmetal equivalents in the synthesis of 1,5-hexadienes.     

Dehydrogenation of alcohols with allyl carbonates catalyzed by palladium or ruthenium complexes

Treatment of alkyl allyl carbonates with a phosphine-free palladium catalyst in acetonltrile affords ketones or aldehydes in high yields. This new method of oxidation of alcohols via allyl carbonates can be applied to various alcohols except simple primary alcohols. The reaction proceeds under neutral conditions and hence various acid- or base-sensitive functional groups are not affected during the reaction. Ruthenium hydride complex is also an effective catalyst. Direct dehydrogenatlon of secondary or allylic alcohols was carried out by the reaction with allyl methyl carbonate by the catalysis of the ruthenium complex. 1,4-Diols and 1,5-diols are converted to lactones with excess allyl methyl carbonate.     

Ruthenium complex-catalyzed allylic alkylation of carbonucleophiles with allylic carbonates

Allylic carbonates except for allyl methyl carbonate reacted with carbonucleophiles such as ethyl acetoacetate in the presence of a catalytic amount of Ru(cod)(cot) [cod = cycloocta-1,5-diene, COT = cycloocta-1,3,5-triene] in N-methylpiperidine at 80°C to give the corresponding monoallylated carbonucleophiles in high yields with high regioselectivity. The regioselectivity was quite different from that in the palladium-catalyzed reactions. The allylation of carbonucleophiles using allyl methyl carbonate selectively gave the diallylated carbonucleophiles in high yields.     

Synthetic Transformations of Higher Terpenoids: X. Intramolecular Cyclization of <Emphasis Type="Italic">N</Emphasis>-Allyl- and <Emphasis Type="Italic">N</Emphasis>-Propargyl-16-dialkylammoniomethyl-12-furfuryl-13,14,15,16-tetranorlabdanoid Bromides

Quaternary ammonium salts obtained by quaternization of lambertian acid 16-dialkylaminomethyl derivatives effected by allyl halides or propargyl bromide undergo intramolecular [4+2]-cycloaddition resulting in diterpenoids of labdane type containing a heterocyclic fragment of 10-oxa-3-azatricyclo[5.2.1.0^1,5]decene or 10-oxa-3-azatricyclo[5.2.1.0^1,5]deca-6,8-diene.     

3,3-Sigmatropic Shifts of Allyl Group Along Cyclopentadiene Ring Perimeter

Reversible non-degenerate 3,3-sigmatropic shifts of the allyl group along the perimeter of the five-membered ring occurring with energy barriers ΔG°≠ = 28.5–30.2 kcal/mol (o-dichlorobenzene-d4) have been detected in the allyl derivatives of 5-methyl-1,2,3,4-tetramethoxycarbonylcyclopentadiene by NMR method. Using DFT B3LYP/6-311++G(d,p) method, it has been shown that degenerate migrations of the allyl group in the related 5-allyl-1,2,3,4,5-pentamethoxycarbonylcyclopentadiene should occur via 3,3-sigmatropic shift through transition states with conformation of a six-membered ring (chair or boat, with close barriers ΔG°≠ = 27.4 or 27.7 kcal/mol, respectively). The simulated higher barrier of alternative 1,5-sigmatropic shifts of the allyl group (ΔG°≠ = 30.8 kcal/mol) indicates the energy preference of the migrations via 3,3-shifts.     

PtCl2-catalyzed tandem triple migration reaction toward (Z)-1,5-dien-2-yl esters

A novel method for the selective synthesis of (Z)-1,5-dien-2-yl esters has been developed though Pt(II)-catalyzed tandem 1,2-acyl and 1,2-hydride migration, along with an allyl migration reaction of propargylic carboxylates with electronically unbiased internal alkynes. The unusual selectivity of 1,2-acyloxy migration was realized.     

Highly stereoselective synthesis of (Z)-1,2-dihaloalkenes by a Pd-catalyzed hydrohalogenation of alkynyl halides

An unprecedented Pd-catalyzed hydrohalogenation of alkynyl halides for the regio- and stereoselective synthesis of (Z)-1,2-dihaloalkenes has been realized using [(allyl)PdCl](2) as the catalyst and cis,cis-1,5-cyclooctadiene as the ligand. The advantages of this protocol are well illustrated by the assembly of trisubstituted (Z)-enynes and multifunctional benzenes via iterative cross-coupling reactions or tandem Diels-Alder-aromatization reactions, respectively.     

Quantitating the effect of an ortho substituent on cyclization and intramolecular hydrogen-transfer reactions of aryl radicals

Reduction of allyl 2-iodobenzyl malonates with triphenyltin hydrides generates aryl radicals that partition between 6-exo cyclization, 7-endo cyclization, and 1,5-hydrogen atom transfer. Rate constants for all of these processes are high (>10(8) M(-)(1) s(-)(1)), and the rates are only marginally reduced (<33%) by the introduction of methyl group ortho to the reacting radical.     

Atom-efficient assembly of 1,5-oxygen-bridged medium-sized carbocycles by sequential combination of a Ru-catalyzed alkyne-alkene coupling and a Prins-type cyclization

Ruthenium-catalyzed coupling of readily accessible 1-trimethylsilyl-1-alkyn-3-ols to allyl ethyl ether followed by in situ ketalization and Lewis-acid induced cyclization affords 1,5-oxygen-bridged eight- and nine-membered carbocycles, products which are difficult to construct with previously published strategies.