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. 2017 Sep 14;53(74):10291-10294.
doi: 10.1039/c7cc06367a.

Effect of protic additives in Cu-catalysed asymmetric Diels-Alder cycloadditions of doubly activated dienophiles: towards the synthesis of magellanine-type Lycopodium alkaloids

Vincent N G Lindsay  1 , Rebecca A Murphy, Richmond Sarpong
Affiliations

Effect of protic additives in Cu-catalysed asymmetric Diels-Alder cycloadditions of doubly activated dienophiles: towards the synthesis of magellanine-type Lycopodium alkaloids

Vincent N G Lindsay et al. Chem Commun (Camb). .

Abstract

The pronounced beneficial effect of a precise amount of protic additive in an enantioselective Cu-catalysed Diels-Alder reaction is reported. This reaction, which employs a cyclic alkylidene β-ketoester as a dienophile, represents one of the first examples of a transformation where these extremely versatile, though highly unstable reaction partners participate effectively in catalytic asymmetric cycloaddition with a functionalised diene. The cycloadduct was used as an intermediate towards the synthesis of magellanine-type Lycopodium alkaloids featuring a Stille cross-coupling of a highly congested enol triflate and a unique Meinwald rearrangement/cyclopropanation sequence.

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Conflict of interest statement

Conflicts of interest

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1
Different stereoinduction models for Cu-catalysed enantioselective Diels–Alder using cyclic alkylidene β-ketoesters.
Scheme 1
Scheme 1
Identification of racemic conditions (a) and evaluation of background reaction upon dilution (b).
Scheme 2
Scheme 2
Preparation of hydrindenone 3 on a larger scale.
Scheme 3
Scheme 3
Use of hydrindenone 3 as key intermediate towards the synthesis of magellaninone.
See this image and copyright information in PMC

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