A Regioselective Cyclohexannulation Procedure via Dienamine [4 + 2] Cycloaddition. Synthesis of Functionalised Decalins

✍ Scribed by Roger L. Snowden; Simon M. Linder; Manfred Wüst

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: German
• Weight: 892 KB
• Volume: 72
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19890720505

✦ Synopsis

1. Introduction. the synthetic application of dienamines I [I]

as Diels-Alder dienes is well documented'). The main features of their reactions with dienophiles are high reactivity and the fact that the R,N group controls the regiochemistry of the cycloaddition. For example, the use of electron-deficient ethylenic dienophiles leads to the selective forma-I 11 Z = electron-withdrawing group -R2NH R" V 111 C02Me VII -Me,NH t. R' 1 C02Me R" m N M e 2 H VI -I ') For a review, see 121; for other examples, see [3]. C02Me 150"/24 h 37 NMe2 (B, 66)

Cf: Scheme 3. CH,=CHCO,Me (1.5 mol-equiv.), toluene. Products isolated after treatment of cycloadduct VI with silica gel (SO', 3 h). For characterisation purpose, dienoates 25-31 were converted to their corresponding carboxylic acids 25a-31a (Exper. Part). Ca. 1 : 1 mixture of (E)-and (Z)-cyclododecenyl double-bond isomers. Racemic mixture, only one enantiomer is shown. Cu. 30: 1 mixture of 1'and 5'-cyclopentenyl double-bond isomers. Cu. 1 :1 diastereoisomeric mixture. Cu. 4:l mixture of 1'and 6-cyclohcxenyl double-bond isomers.