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

Abstract

Aldol-type addition of α-triethylsilyl-α-diazoacetone was achieved under nucleophilic activation by tetrabutylammonium fluoride (TBAF). The use of a semistoichiometric amount of TBAF (protocol P1) provided the corresponding β-hydroxy-α-diazoacetone as the sole product. Alternatively, the use of a catalytic amount of TBAF led to a mixture of β-hydroxy- and β-silyloxy-α-diazoacetone products, which was cleanly desilylated with Et3N·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.

Soluble individual metal atoms and ultrasmall clusters catalyze key synthetic steps of a natural product synthesis

“…With 10 in hand, we tested different reactions to couple piperaldehyde and thus leave a free alcohol group for the later cyclization reaction (Fig. S9), however, none of the reported conditions [39][40][41] worked in our hands.…”

Preparation and Carbocupration–Silylation of Allyl Propiolates: Vicinal Functionalization To Form Polysubstituted (E)-Vinylic Silanes

“…28,29 Another potential application is to employ allylic ester variants in Ireland-Claisen rearrangements, giving access to stereodefined α-silyl-β,γ-γ',δ'-unsaturated carboxylic acids (Scheme 1). Such acids could present a polyfunctionlized scaffold for elaboration via desilylative aldol additions, 30 ring-closing lactonizations/lactamizations, 31,32 or amidations for abiotic peptide synthesis. 33,34 Herein we report our results on the carbocupration of allylic propiolates to form novel (E)-αtrialkylsilyl-β-alkyl-α,β-unsaturated allylic esters (Scheme 2) and also demonstrate a representative Ireland-Claisen rearrangement to generate an α-allyl-α-trialkylsilyl-γ-alkyl-β,γ-unsaturated carboxylic acid.…”

Function-Oriented Synthesis toward Peloruside A Analogues

“…At first, low-temperature LDA-induced methyl-side aldolizations were performed between aldehydes ( R )- 1a or ( R )- 1b and TES-diazoacetone 2 , prepared in three steps on a multigram scale . Desilylation of any remaining C-protected diazoaldols was ensured by methanolysis on the crude products, providing aldols 14a (R = Et) and 14b (R = Me) as inseparable mixtures of two diastereoisomers.…”

“…At first, low-temperature LDA-induced methyl-side aldolizations were performed between aldehydes (R)-1a or (R)-1b and TES-diazoacetone 2, prepared in three steps on a multigram scale. 19 Desilylation of any remaining C-protected diazoaldols was ensured by methanolysis on the crude products, providing aldols 14a (R = Et) and 14b (R = Me) as inseparable mixtures of two diastereoisomers. Absolute configurations of major (15S)-14 and minor (15R)-14 diastereoisomers were attributed on the basis of Mosher's esters study on the diastereoisomeric mixtures (see the SI).…”