Monday, April 25, 2011

Methyl Carbamate and tert butyl ester in the synthesis of (-) kainic acid

Amine as methyl carbamate:  T. Fukuyama's group converted an acid into a methyl carbamate protected amine by using a Curtius rearramgement. 
Installation: DPPA, NEt3, toluene, reflux then MeOH, reflux, 78% yield
Survived: Base (LiHMDS at -78 C), Zn/AcOH, LiAlH(Ot-Bu)3, TMSCN with BF3.OEt2
Removal: aq. NaOH, reflux , 70% yield
Reference: Organic Letters, 2011, 13, 2068.

Acid as tert-butyl ester: T. Fukuyama's group used a tert-butyl ester which came from commercially available tert-butyl bromoacetate.
Installation: Commercially available tert-butyl bromoacetate
Survived: Zn/AcOH, LiAlH(Ot-Bu)3, TMSCN with BF3.OEt2
Removal: aq. NaOH, reflux , 70% yield
Reference: Organic Letters, 2011, 13, 2068.

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