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The intramolecular Diels–Alder reaction of N-acylvinyl imidates provides a rapid entry into cis-fused hexahydroisoquinolones. This methodology has been used in a concise synthesis of the yohimbine alkaloid (±)-alloyohimbane.

Thioisomunchnone dipoles were generated by the reaction of bromoalkenoyl chlorides with thioamides. The intramolecular dipolar-cycloaddition reaction was used for a short synthesis of the yohimbanoid alkaloid (±)-alloyohimbane.

International audience; [reaction: see text] The pharmacologically important tetracyclic berbane and pentacyclic alloyohimbane structures were prepared efficiently in four steps including a stereoselective 6-exo radical cyclization using xanthates as the radical source.

[reaction: see text] The pharmacologically important tetracyclic berbane and pentacyclic alloyohimbane structures were prepared efficiently in four steps including a stereoselective 6-exo radical cyclization using xanthates as the radical source.

A short and stereoselective synthesis for both dl -alloyohimbane and dl -epialloyohimbane using one and the same starting compound is presented.

[reaction: see text] The reaction of alpha-sulfonyl acetamide 1 with various cyclic unsaturated esters 2 to fused bicyclic glutarimides is reported. Syntheses of (+/-)-alloyohimbane (4) and louisianin D (5) have been accomplished.

The intramolecular Diels–Alder reaction of N-acylvinyl imidates provides a rapid entry into cis-fused hexahydroisoquinolones. This methodology has been used in a concise synthesis of the yohimbine alkaloid (±)-alloyohimbane.

A conceptually novel total synthesis of (−)-alloyohimbane is reported. The key step utilizes a group-selective nitrogen insertion process on a meso bicyclic ketone.

The intramolecular annulation of malonic acid derivatives of 4-aminomethyl cyclohexenones is shown to be an efficient route to 3,6-diketoderivatives of cis perhydroisoquinolines.

A simple method for the stereoselective synthesis of yohimbane (7) and alloyohimbane (5) via the diazoketone (2) from the anhydride (8), a symmetrical starting material, was examined. The preparation of pentacyclic ring systems contained in yohimbine and reserpine would be possible for the synthesis of such alkaloids by this method.

The pro-(R) enantiotopic specificity of pig liver esterase-catalysed hydrolysis of the meso-diacetate (2) to give (3) enables this chiron to be used in a higly efficient enantioselective synthesis of the natural (–)-alloyohimbane (1).

The intramolecular annulation of malonic acid derivatives of 4-aminomethyl cyclohexenones is shown to be an efficient route to 3,6-diketoderivatives of cis perhydroisoquinolines.

The pro-(R) enantiotopic specificity of pig liver esterase-catalysed hydrolysis of the meso-diacetate (2) to give (3) enables this chiron to be used in a higly efficient enantioselective synthesis of the natural (–)-alloyohimbane (1).