European Journal of Organic Chemistry

The cover picture shows the comparison between the fashion designs made with tailored fabrics and the solid-phase synthetic platform we propose. The similarity arises from the capacity of the synthetic platform to perform the customized design of the alkyl thiols made to your convenience like the patterns made by a tailor for a specific customer. The background of the picture simulates the texture of a fabric to enhance this comparison. Details are discussed in the article by F. Albericio et al. on p. 1233 ff.

Tetrahydropyrans are subunits in a wide range of biologically active natural products. Prins-type cyclization reactions, in which a π-nucleophile adds to an appended oxocarbenium ion, are effective for constructing these rings. This microreview covers variations of this reaction that have been applied to natural product synthesis with a focus on the method of oxocarbenium ion formation and type of π-nucleophile.

A pillar[5]arene-based heteroditopic receptor containing an anion recognition site promotes the binding affinity to n-octyltriethylammonium salts in chloroform, whereas the corresponding monotopic host shows weak binding abilities with these guests. The urea group and the macrocyclic unit not only provide positioned binding sites but also induced positive cooperative effects for contact ion pairs.

Click chemistry in its “hot” version: A one-step approach to nucleosides opens the way to the development of a new class of positron emission tomography (PET) tracers.

A new synthetic approach to amide bond formation through the oxidative coupling of N,N-dialkylformamides with carboxylic acids was achieved by using a copper catalyst and aqueous tert-butyl hydroperoxide (TBHP) as a sacrificial oxidant. Furthermore, this method was applied in the coupling of chiral amino acids in which the stereochemistry was retained in the resulting amide products.

The synthesis of triazolo[1,5-a][1,4]benzodiazepinones by employing a post-Ugi Cu-catalyzed tandem azide–alkyne cycloaddition (AAC)/Ullmann coupling strategy is elaborated. The intramolecular trapping of the N–Cu intermediate, formed by the CuAAC, leads to the formation of the C–N bond through Ullmann coupling and gives a novel and efficient route for the synthesis of triazolobenzodiazepinones.

The palladium-catalyzed [¹¹C]carbonylation of aryl halides and triflates was achieved at atmospheric pressure by employing xantphos as the supporting ligand. Aryl halides were converted into their corresponding [¹¹C]amides in good to excellent yields. The conditions were also successfully employed in the radiolabeling of an [¹¹C]ester, a [¹¹C]carboxylic acid, an [¹¹C]aldehyde, and a [¹¹C]ketone.

This paper describes a straightforward and inexpensive method based exclusively on solid-phase synthesis for the preparation of a variety of customized alkanethiols (ATs). The technique allows a variety of ATs to be obtained in only three steps, overcoming the difficulties encountered during their preparation in solution.

An inherently chiral aminomethylated resorcin[4]arene was used as a chiral scaffold to synthesize urea- and amide-functionalized derivatives. Introduction of chiral (S)-(–)-1-phenylethylurea side chains afforded diastereomeric macrocycle hosts; these were subjected to chiral recognition studies that revealed an R/S selectivity of 1.4 for an enantiomeric mandelic acid guest.

Cyclizations on the lactam carbonyl from tryptophanol-derived oxazolopiperidone lactams have been studied. A pyridine ring fused to the piperidone moiety exerts a dramatic effect on the regioselectivity of the cyclization, leading exclusively to α-amidoalkylation products.

A new 1,6-hexylene-bridged bis-N-heterocyclic carbene Pd^II complex was prepared and characterized. The catalytic activities of this complex in Suzuki–Miyaura and Heck–Mizoroki reactions were investigated.

The cyclization of 2-(aminomethyl)aniline, methyl 3,3,3-trifluoropyruvate, and various oxo compounds afforded linearly annulated pyrroloquinazolines as the major product along with angularly annulated products. The temperature was observed to affect the ratio of the two cyclization products. Some of the linear pyrroloquinazolines were stereoselectively didehydrogenated by the trifluoropyruvate.

The synthesis of C-5-substituted cytidine and of C-8-substituted adenosine and guanosine morpholino nucleoside monomers by means of Pd-catalyzed cross-coupling (Sonogashira, Suzuki, and Heck) reactions is described. Various types of alkyne, aryl, and alkene group have been used to obtain diversely functionalized monomers from the corresponding iodo or bromo derivatives.

Indium-mediated propargylation of chiral N-tert-butanesulfinylimines with 3-bromo-1-trimethylsilyl-1-propyne in THF under sonication proceeds diastereoselectively in good yields.

A novel protocol for the preparation of 1,5,6-trideoxy-1,5-imino-L-mannitol and 1,5,6-trideoxy-1,5-imino-D-glucitol is reported. The key steps include organocatalyzed syn-selective direct aldol reaction of hydroxyacetone and CBz-protected isoserinal hydrate, followed by reductive amination/cyclization.

The stereoselective synthesis of 5-hydroxy- and 4,5-dihydroxypipecolic acids was accomplished by sequential Pd-catalysed methoxycarbonylation and stereoselective reduction of enantiopure hydroxylated lactam-derived enol phosphates obtained from both enantiomers of commercially available γ-hydroxymethyl-γ-butyrolactone and 2-deoxyribose.

A new synthetic approach to 9,10-anthraquinones was developed. Selective Claisen condensation of an allyl γ-dioxinyl-β-oxo ester with arylacetyl chlorides, Pd-catalyzed deallylation, decarboxylation and aromatization gave 6-(arylmethyl)resorcylates. Subsequent acid-mediated cyclization and oxidation with CAN gave target anthraquinones, one of these being the fungal natural product macrosporin.

α-Nitrocycloalkanones gave high-yielding “on-water” Michael addition reactions to α,β-unsaturated aldehydes and ketones. The scope of the method was extended to cyclic enones and unsaturated esters, nitriles and sulfones by use of very dilute aqueous solutions of potassium carbonate as the reaction media.

The first phosphane-free, heterogeneous, atom-efficient cross-coupling reaction of triarylbismuth compounds and acyl chlorides was achieved in N-methylpyrrolidone with Bu₃N as the base at 80 °C in the presence of 1.5 mol-% MCM-41-immobilized bidentate nitrogen palladium complex [MCM-41–2N-Pd(OAc)₂] to yield a variety of unsymmetrical biaryl ketones in good to excellent yields.

Five@Once: A new method to access dipiperidine and piperidino-quinolizidine alkaloids was established within the total syntheses of virgidivarine (1) and virgiboidine (2). The key step includes a Ru-mediated intramolecular (tandem) ene-ene-yne ring-rearrangement metathesis/oxidation process, in which a sequence of five reactions occur in a single vessel with one catalyst source.

The total synthesis of Hirtellanine A was achieved. The synthesis featured a one-pot, tandem acid-mediated deprotection and tautomerization cascade for the construction of the coumaronochromone motif, and a regioselective Claisen rearrangement for the benzopyran construction.

An efficient protocol for the ortho-aroylation of 2-arylbenzothiazoles and 2-arylbenzoxazoles has been developed using aldehydes as the aroyl source. This Pd-catalyzed C–H bond functionalization occurs in the presence of tert-butyl hydroperoxide, and a variety of functional groups on the 2-arylbenzothiazoles, 2-arylbenzoxazoles, and aldehydes are tolerated under the reaction conditions.