1,4-Dioxaspiro[4.5]decan-8-one → 8-Benzylidene-1,4-dioxaspiro[4.5]decane
Reaction equation
[Br-].[C:2]1([CH2:8][P+](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C([Li])CCC.[CH2:33]1[O:43][C:36]2([CH2:41][CH2:40][C:39](=O)[CH2:38][CH2:37]2)[O:35][CH2:34]1>>[C:2]1([CH:8]=[C:39]2[CH2:40][CH2:41][C:36]3([O:43][CH2:33][CH2:34][O:35]3)[CH2:37][CH2:38]2)[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1Participants
Procedure
For example, when n is the bridging group --CH2--, an appropriately substituted or unsubstituted phenylmethyl bromide, for example, 2-chlorophenylmethyl bromide, is reacted with triphenylphosphine in toluene, affording the corresponding phenylmethyltriphenylphosphonium bromide. The so-prepared phosphonium bromide is then treated with n-butyllithium, and reacted with 1,4-cyclohexanedione mono-ethylene ketal, yielding the appropriate 8-phenylmethylene-1,4-dioxaspiro[4.5]-decane. The 8-phenylmethylene-1,4-dioxaspiro[4.5]decane is in turn reduced with hydrogen gas in the presence of 10% palladium on charcoal, giving the corresponding 8-phenylmethyl-1,4-dioxaspiro[4.5]-decane. The 1,4-dioxaspiro functional group is then cleaved from the so-prepared molecule with acetic acid and water, affording the corresponding 4-phenylmethylcyclohexanone. The 4-phenylmethylcyclohexanone is then reacted with cyanoguanidine, as previously described, yielding the targeted 2,4-diamino-6-phenylmethyl-5,6,7,8-tetrahydroquinazoline. Example 2 provides a detailed description of how this reaction is conducted.
Sources & evidence
- ORD record
- ord-021149c54d114adaa90dce957f1c1006
- Source dataset
- uspto-grants-1996_07
- Patent number
- US05536725
Reaction notes
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