Dane’s diene

The asymmetric Diels-Alder cycloadditions of enantiopure (5)-5-(/ -tolylsulfinyl)-1,4-benzoquinones with Dane s diene under thermal and Lewis acid conditions produce tetracyclic quinones after spontaneous elimination of the sulfinyl group.The Diels-Alder reaction of barrelene with o-benzoquinone produces tetracyclo[6.2.2.2 .0 ]tetradeca-9,ll,13-triene-4,5-dione. Under kinetic control, the Diels-Alder cycloaddition of 2,3-dicyano-p-benzoquinone (98) with cyclopentadiene in MeOH produces the single cycloadduct (99) (Scheme 38). ... 

Scheme 1-7 Analysis of the relative orientation of Dane s diene 14 and the complementary dienophile following Robinson s way.

Alkylation of the metallated enol derived from 52 with m-methoxy-phenylethyl-iodide to afford the tricyclic jj-keto ester 53, followed by cationic cydization of this to furnish the steroid derivative 54, warrants particular attention. Corey and colleagues have recently published another total synthesis of 40 [82], beginning with an enantioselective Diels-Alder reaction between Dane s diene 14 and dienophile 61. An oxazaborolidinium salt (see Section 1.3.2.3) was used as an efficient catalyst (Scheme 1-14). 

Scheme 1-14 Collection of formulae relevant to a synthesis of (—)-desogestrel 40 opened by an asymmetric Diels-Alder reaction of Dane s diene 14 and dienophile 61.

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