Acid-catalyzed equilibration of spiroketals 5SHp6 and 55Haj3 involves a two stage process whereby the 1,6-dioxaspiro]4.4]nonanes can be equilibrated under mild conditions to a pair of 1,6\_dioxaspiro[45]decanes with preservation of the adjacent C-20 methyl stereocenter. Under more forcing conditions
Chemico-enzymatic syntheses of racemic and chiral isomers of 7- methyl-1,6-dioxaspiro[4.5]decane
โ Scribed by Sowmianarayanan Ramaswamy; Allan C. Oehlschlager
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- French
- Weight
- 375 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0040-4020
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โฆ Synopsis
Porcine pancreatic lipase (PPL) mediated resolution of 6-heptene-2-ol afforded the enantiomers in high optical purities. Alkylation products of the dianion of the 2-4'-hydroxypentyl-1,3dithiane prepared from the enantiomers, followed by alkylative hydrolysis, afforded 97% optically pure E-7-methyl-1,6-dioxaspiro[4.5]decane.
๐ SIMILAR VOLUMES
E)-and (Z)-2-methoxyca\_rbonylmethylene-l,6-dioxaspiro[4.5]decanes have been synthesized from an aeydie keto alcohol possessing an alkynoate past via intr, maoleculat conjugate addition. Unde~ thermodynamically controlled conditions using t-BuOK in THF, the (E)-isomer could be obtained in 52:1 ratio
A diastereoselective approach to (2R,5S)-and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane 1 and 1a is described. The route starts with an alkylation reaction among the cyclopentanone N,N-dimethylhydrazone 6 and the chiral iodides (R)-3 or (S)-3, derived from the enantiomers of ethyl b-hydroxybutyrate,