Bis-oxazolyl methanols

Crews and co-workers ° employed a 2-lithiooxazole in a key step of their synthetic strategy to prepare bengazole A 904, an antihelminthic agent isolated from marine sponges. Lithiation of 901 at —50°C followed by addition of 5-oxazolecarboxaldehyde 902 gave the bis-oxazolyl methanol 903 (Scheme 1.241). Acylation of 903 with myristoyl chloride and deprotection completed the synthesis of 904. 

Shioiri s group also employed a 2-lithiooxazole to construct the bis-oxazolyl methanol core of 904. Here, lithiation of a silyl-protected 4-oxazolemethanol 905a/ b followed by condensation with 902 afforded a racemic bis-oxazolyl methanol 906a/b in modest yield (Scheme 1.242). Attempts to improve the yield of 906 using a Lewis acid to coordinate the oxazole nitrogen, alternate bases, or addition of cosolvents were not successful. Barton-McCombie radical deoxygenation was used... 

Maneb (manganese ethylene bis-dithiocarbamate) -93, 119, 120,128, 135,178,227 Mercuric chloride -168,169 Mercurous chloride -168,169 Metalaxyl (N-(2,6-dimethylphenyl) -N-(methoxyacetyl)alanine methyl ester) -123, 237,238 Methanol [[[2-(dihydro-5-methyl-3(2H)-oxazolyl)-1-methyl-ethoxy] methoxy] methoxy] -76... 

---