Configurational Stability and Stannylation of Dipole-Stabilised Cyclic Tertiary Benzylic α-Oxycarbanions, which Occurs with Retention or Inversion of Configuration Depending on R and X of R3SnX Used
✍ Scribed by Friedrich Hammerschmidt; Achim Hanninger; Biljana Peric Simov; Horst Völlenkle; Andreas Werner
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 389 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
2,4,6-Triisopropylbenzoates of 1-indanol and 1-tetralol (ee stannane 7 (de Ն 95%) with inversion. The carbanion derived from (S)-1-indanyl N,N-diisopropylcarbamate (9) is 98%) are deprotonated at -78 °C in hexane by sBuLi/TMEDA to give partly configurationally labile organolithium configurationally stable. It reacts with trimethyltin chloride favouring inversion of configuration (ee up to 17%). intermediates 5a and 5b, which are deuterated by MeOD with retention of configuration. These intermediates are Tributyltin chloride and tributyltin triflate yield stannanes 11b of opposite stereochemistry, the latter giving retention of stannylated by trimethyltin chloride with inversion as determined by lithiodestannylation followed by addition of configuration. Tributyltin bromide behaves similarly to the chloride, but the ee of the reaction product is only about 30%. MeOD to produce deuterated esters of low ee. Stannylation of (S)-5b with (-)-menthyldimethyltin bromide affords sparteine with a variety of electrophiles. In the case of the This work deals with the configurational stability and the [a] Institut für Organische Chemie der Universität Wien, stereochemistry of stannylation of benzylic carbanions be-Währingerstraße 38, A-1090 Wien, Austria