Sodium triacetoxyborohydride → (9-((4-(2-(tert-Butyldimethylsilyloxy)ethyl)thiophen-2-yl)methyl)-1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)(5-methylthiophen-2-yl)methanone

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Reaction Steps

(5-Methylthiophen-2-yl)(1-oxa-4,9-diazaspiro[5.5]undecan-4-yl)methanone trifluoroacetate (example 9, step b) (0.230 g) was added to a stirred solution of a 4:1 mixture of 4-(2-(tert-butyldimethylsilyloxy)ethyl)thiophene-2-carbaldehyde and 3-(2-(tert-butyldimethylsilyloxy)ethyl)thiophene-2-carbaldehyde (example 27, step b) (0.20 g) and AcOH (0.033 mL) in N-methyl-2-pyrrolidinone (3 mL). After 5 min, sodium triacetoxyborohydride (0.35 g) was added. After 16 h water was added and the mixture extracted with ethyl acetate. The ethyl acetate layer was washed three times with water and evaporated in vacuo. Purification by silica gel chromatography eluting with 20:80:5 ethyl acetate:isohexane:triethylamine, separated the two isomeric products and gave the subtitled compound as a gum. Yield 0.21 g.

Provenance & Evidence