Synthesis and Reactivity of Mixed Alkynylalanes by Direct Triethylamine-Catalyzed Alumination of Terminal Alkynes

Abstract

[reaction: see text] Terminal alumination of alkynes by DIBALH or trimethylaluminum can be performed in a simple manner in the presence of a small amount of triethylamine. This new Lewis-base-catalyzed process delivers mixed alkynyldialkylalanes of great interest, without the need of an initial deprotonation step with lithium or sodium derivatives followed by a transmetalation.

Gold(I)-catalyzed hydration of allenes

“…All reagents were purchased from major suppliers and used as received. Tridec-7-yn-6-ol,18 o -nitrobenzenesulfonyl hydrazine,19 ethyl 3-hexyl-3,4-pentadienoate,20 4-(4-(trifluoromethyl)phenyl)-3-butyn-2-ol,21 2,3-pentadienyl benzoate ( 2 ),13 1-phenyl-1,2-butadiene ( 4 ),13 dimethyl 2-(2,3-butadienyl)malonate ( 10 ),13 and 1-(benzyloxy)-2-(5-methyl-3,4-hexadienyl)benzene ( 16 )13 were prepared employing published procedures.…”

Combining NHC–Cu and Brønsted Base Catalysis: Enantioselective Allylic Substitution/Conjugate Additions with Alkynylaluminum Reagents and Stereospecific Isomerization of the Products to Trisubstituted Allenes

“…We began by probing transformations that involve the alkynylaluminum reagent generated in situ by reaction of phenylacetylene, di- iso -butylaluminum hydride (dibal-H) and 5.0 mol % Et 3 N. [13] Trisubstituted allylic phosphates ( 2a - j , Table 1) undergo reaction to afford the desired enynes ( 3a - j ) in 58-98% yield and 90:10-98.5:1.5 e.r. ; >98% S N 2′ selectivity is observed except for cyclohexyl-substituted 3j (95:5 S N 2′:S N 2, entry 10, Table 1).…”

Cross‐Coupling Reactions to sp Carbon Atoms

“…They are accessible by transmetallation of the corresponding lithium or sodium acetylide with dialkylaluminum chloride compounds. Novel preparation techniques circumvent strongly basic conditions by using an Et 3 N-catalyzed metallation reaction of terminal alkynes without the need for prior deprotonation [351]. The propensity of alkynylaluminum reagents for cross-coupling was demonstrated by employing [RC≡CAlEt 2 ]-type reagents (Table 9.23).…”