TBAF-Triggered Aldol-Type Addition of α-Triethylsilyl-α-diazoacetone

Aldol-type addition of alpha-triethylsilyl-alpha-diazoacetone was achieved under nucleophilic activation by tetrabutylammonium fluoride (TBAF). The use of a semi-stoichiometric amount of TBAF (protocol P1) provided the corresponding beta-hydroxy-alpha-diazoacetone as the sole product. Alternatively, the use of a catalytic amount of TBAF led to a mixture of beta-hydroxy- and beta-silyloxy-alpha-diazoacetone products, which was cleanly desilylated with Et3N center dot 3HF (protocol P2). The weakly basic conditions employed tolerate a wide range of substrates and constitute a high-yielding, convenient complementary procedure to the low-temperature LDA-promoted aldol-type addition of diazoacetone.