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The reactivity of novel chiral lactamide‐substituted diselenide‐based reagents under oxidative conditions was exploited to develop a metal‐free method for the preparation of enantioenriched allenylamides from simple alkynes in good yields, and with enantiomeric excesses up to 99 %. The key of the success in this method is attributed to the hydrogen‐bonded lactamide appendages that ensure configurational stability of chiral vinyl selenoxide intermediates for an optimal enantiotopic β‐syn‐elimination step. [ABSTRACT FROM AUTHOR]

Many natural products of plant or microbial origins are derived from enzymatic dearomative oxygenation of 2‐alkylphenolic precursors into 6‐alkyl‐6‐hydroxycyclohexa‐2,4‐dienones. These so‐called ortho‐quinols cyclodimerize via a remarkably selective bispericyclic Diels–Alder reaction. Whether or not the intervention of catalytic or dirigent proteins is involved during this final step of the biosynthesis of these natural products, this cyclodimerization of ortho‐quinols can be chemically reproduced in the laboratory with the same strict level of site‐specific regioselectivity and stereoselectivity. This unique yet unified process, which finds its rationale in the inherent chemical reactivity of those ortho‐quinols, is illustrated herein by an efficient and bioinspired first chemical synthesis of one of the most structurally complex and synthetically challenging examples of such natural cyclodimers, the bisditerpenoid (+)‐maytenone. [ABSTRACT FROM AUTHOR]

Under high pressure, this transition state leads to the product, the natural (+)-maytenone, which was first isolated from the plant I Maytenus dispermus i , here appearing in the background image. Asymmetric synthesis, cycloaddition, hypervalent compounds, total synthesis, transition states Keywords: asymmetric synthesis; cycloaddition; hypervalent compounds; total synthesis; transition states EN asymmetric synthesis cycloaddition hypervalent compounds total synthesis transition states 15111 15111 1 06/23/21 20210625 NES 210625 B From the teaching class b with the bispericyclic Diels-Alder reaction of I ortho i -quinols drawn on the chalk board to the laboratory with the (+)-ferruginol substrate and a chiral bisiodyl reagent in the flask: The single I ortho i -quinol diastereomer thus produced combines in pairs to reach a I C i SB 2 sb -symmetric transition state in which [4+2] and [2+4] processes are equivalent, as described by Laurent Pouységu, Stéphane Quideau, and co-workers in their Research Article on page 14967. [Extracted from the article]