A facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed under basic, neutral and acidic conditions using N,N-dimethylaminopyridine (DMAP), tetrabutylammonium tetrafluoroborate (TBABF₄) and BF₃·Et₂O, respectively. A calcined hydrotalcite was also used instead of DMAP. Finally, to test the scope of the protocol in the synthesis of biologically relevant macrolactones, the total synthesis of Sansalvamide A was carried out.

An air-stable phosphinito palladium(II) complex (Ph1-Phoxide) has been found to be an efficient catalyst in the formation of C–C bonds. The coupling of terminal alkynes formed gem-1,3-enynes as the only reaction products. Aromatic alkynes can be synthesized from the coupling of terminal alkynes and haloaromatic compounds (Sonogashira coupling). The phosphinito palladium(II) complex also catalyses the coupling between acyl chlorides and terminal alkynes (Sonogashira coupling), furnishing ynones in excellent yields.

The synthesis of amides by coupling benzotriazole esters and amines can be achieved conveniently in moderate to excellent yields (50–95%) using a commercial, synthesized, calcined or reconstructed Mg–Al hydrotalcite instead of one of the classic bases (tertiary amines). The experimental results demonstrated that commercial and synthesized hydrotalcite can be quantitatively recovered from the reaction by simple filtration and reused for a number of cycles and that the reconstructed hydrotalcite is the most active form for the amide bond formation. Finally, to test the scope of the protocol for the synthesis of biologically relevant molecules, the total synthesis of Sansalvamide A was carried out.

Herein, we describe a simple and practical protocol for the reduction of carboxylic acids via the in situ formation of hydroxy­benzotriazole esters followed by reaction with sodium borohydride to give the corresponding alcohols. The reaction proceeds with excellent yields in the presence of water.

Three new diarylbutane lignans, named 9-acetyl-9′-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of ¹H and ¹³C NMR spectra.

Benzotriazole esters formed in situ were found to be efficient intermediates in the esterification of tertiary alcohols using 4-(dimethylamino)pyridine (DMAP) as the base. These mild and basic reaction conditions allow the conversion of various substrates into esters in good yield.