Spiro decane derivative

Adam, G., Cesura, A., Kolczewski, S., Roever, S., Wichmann, J. (F. Hoffmann-La Roche AG) Di- or triaza-spiro(4,5)decane derivatives, EP963985 (1999c). 

Alkyl(aryl)imino-6-amino-6-carboethoxy-5-oxo-37/,47/-l,3,4-thiadiazines 165 afford the spiro[5.4]decane derivatives 166 upon reflux with aryl isothiocyanates in ethanolic sodium hydroxide solution (Equation 21) <1999IJB932>. 

Intramolecular radical dearomatization has been examined as a route to spirocyclic ring systens. Spiro[4.5]decane derivatives have been obtained fi-om a tand radical addition process initiated by Mn(OAc)j (Scheme 15.9) [21]. Yields of spirocyclic products were highest when substituents on the intermediate cyclohexadienyl radical (e.g., OMe in 26) could promote subsequent oxidation to stable cyclohexadiene products via cation 27. Related ring systens have been prepared undo-... 

Ring Expansion and Cleavage of Succinoln Derivatives Spiro[4.5]decane-l,4-dione and Ethyl 4-Cyclohexyl-4-oxobutanoate... 

Dynamic kinetic resolution processes (DKR) [50] have been also carried out successfully using (5)-proline as catalyst. Thus, racemic atropisomeric W-diisopropyl-2-formylbenzamide derivatives reacted with excess of acetone (27.3 equiv.) in DMSO at room temperature to gave mixtures of diastereoisomers from 36% to 78% de, with the major diastereoisomer reaching up to 95% ee [51]. In a similar way, DKR of racemic l,4-dioxa-8-thia-spiro[4.5]decane-6-carbaldehyde (18) was performed with an excellent enantioselectivity using ketone 14 as the source of nucleophile (Scheme 4.7) [52]. The protocol has been successfully extended to the related 6,10-dicarbaldehyde, as a mixture of racemic and mexo-compounds. 

The synthesis of (+ )-sesquifenchene (450) and of ( )-epi-P-santalene (451) from the common intermediate (449), derived from endo-dicyclopentadiene, has been detailed. Conversion of (449) into the precursor of (450) makes use of the skeletal rearrangement that occurs during solvolysis of active 2-norbornyl esters. In a synthesis of (-H )-hinesol (452) and 10-epi-(-l-)-hinesol, interesting use has been made of a fragmentation reaction.The tosyl derivative (453), which was obtained in several steps from ( —)-P-pinene, was converted into the spiro[4,5]decane (455) on treatment with sodium hydride in DMSO the essential stereoelectronic changes are summarized in the intermediate (454). 

The synthesis of agarospirol (epihinesol) portrays an efficient stereoselective approach to spiro[4-5] decanes based on the intramolecular keto-carbene insertion reaction (A— B) and cleavage of the derived cyclopropyl alcohol (C) to give a spiroketone. 

Recently Yamada et afi described a facile method of preparing the properly functionalized spiro[4-5] decane system by acid catalyzed cyclization of cyclohexenone derivatives, and applied it to the synthesis of / -vetivone. The clever use of proximity effects is a noteworthy feature of this ingenious synthesis. 

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