Synthesis of tryptamine derivatives via a direct, one-pot reductive alkylation of indoles.

An efficient, one-pot reductive alkylation of indoles with N-protected aminoethyl acetals in the presence of TES/TFA is reported. It represents the first general method for the direct synthesis of tryptamine derivatives from indoles and nitrogen-functionalized acetals. This convergent and versatile approach employs safe and inexpensive reagents, proceeds under mild conditions, and tolerates several functional groups. The new procedure was efficiently applied to a gram-scale synthesis of both luzindole, a reference MT2-selective melatonin receptor antagonist, and melatonin.

Direct, one-pot reductive alkylation of anilines with functionalized acetals mediated by triethylsilane and TFA. Straightforward route for unsymmetrically substituted ethylenediamine.

A new, robust, and reliable method has been developed for the selective reductive N-alkylation of primary and secondary aromatic amines with some functionalized acetals using TFA/Et(3)SiH as a reagent combination. A variety of unsymmetrically substituted ethylenediamines can be synthesized in a one-pot procedure in excellent yields at room temperature. This new procedure offers significant advantages over previous synthetic approaches, including brevity, mild reaction conditions, excellent yields, and high functional group tolerance.

Direct, regioselective, and chemoselective preparation of novel boronated tryptophans by Friedel-Crafts alkylation.

A facile synthetic approach to the direct preparation of various novel unnatural boronated protected tryptophans using a regio- and chemoselective electrophilic substitution of 4- and 5-boronated indoles with N-protected dehydroalanine is described. The gram-scale synthesis of two free tryptophan boronic acids is also reported.

A novel one-pot approach of hexahydropyrrolo[2,3-b]indole nucleus by a cascade addition/cyclization strategy: synthesis of (+/-)-esermethole.

A practical and efficient synthesis of 3-substituted hexahydropyrrolo[2,3-b]indole is described. The addition/cyclization of 3-substituted indoles with alpha,beta-dehydroamino esters in the presence of a Lewis acid provides hexahydropyrrolo[2,3-b]indole adducts in good yields and stereoselectivities. This approach has been applied to the concise synthesis of esermethole employing an appropriately substituted indole and an N-acyl dehydroamino ester.