Substitutions‐ und Additionsreaktionen an silylierten Acetylenen

Abstract

Bei Einwirkung von Slurehalogeniden oder -anhydriden auf bis-silylierte Acetylene, wie z. B. Bis-trimethylsilyl-acetylen (I), wird unter Bildung von silylierten Alkinonen nur ein Silylrest durch eine Acylgruppe substituiert. Umsebung von I mit a-Chlor-alkylathern ergibt jedoch durch Substitution beider Silylreste Bisalkoxy-alkine. In mono-silylierten Acetylenen, z. B. im Trimethylsilyl-phenylacetylen, ist die Silylgruppe ebenfalls gegen einen Acylrest austauschbar. Addition von Aziden wie Trimethylsilyl-bzw. Phenylazid an Silylacetylene fiihrt zu silylierten 1.2.3-Triazolen. Bei diesen erfolgt bereits durch Einwirkung von Methanoi in der Kllte die Abspaltung der N-Silylgruppe, wtihrend die C-Silylgruppe erst durch langeres Behandeln mit methanolischer Saure abgespalten wird. Der Reaktionsmechanismus bei der Entstehung der silylierten Alkinone wird diskutiert.

Iron‐Catalyzed Synthesis of β‐Chlorovinyl and α,β‐Alkynyl Ketones from Terminal and Silylated Alkynes with Acid Chlorides

“…In contrast, the reaction of benzoyl bromide with hex-3-yne in the presence of 10,20 and 50% of FeCl 3 under the standard reaction conditions afforded a mixture of b-bromo-and b-chloroalkenyl ketones as shown in Scheme 3. These results clearly show that the chloride in FeCl 3 is incorporated in the final product and support the proposed step-wise mechanism in Scheme 2.…”

“…2-Fluoro-, 4-fluoro-, 4-bromo-, and 4-chlorobenzoyl chlorides 1f, 1g, 1h and 1l provided 5f, 5g, 5h and 5i on reaction with 2k in 77, 81,79 and 76% yields, respectively (entries [6][7][8][9]. Under similar reaction condition, ortho-, meta-, para-tolyl(trimethylsilyl)acetylenes 2l, 2m and 2n reacted with 1b to to produce 5j, 5k and 5l in 66, 71 and 78% yields, respectively (entries [10][11][12]. Similarly, thiophene-2-carbonyl chloride (1i) gave 5n in 78% yield (entry 14).…”

“…Finally when temperature and play a crucial role as key intermediates in the synthesis of natural products [9b-e] and heterocyclic compounds. [9f-o] Various methods for the synthesis of [10] alkynones have been typically synthesised by transition metal-catalyzed cross-coupling reactions of acid chlorides and terminal alkynes. [11] Alternatively, the cross-couplings of acid chlorides with the corresponding organometallic reagents and carbonylative coupling reactions have attracted much attention.…”

Metal‐Free 1,5‐Regioselective Azide–Alkyne [3+2]‐Cycloaddition

“…alkyne cycloadditions have been applied. [13] Notably, the TMS-group can lead to a high selectivity considering 4-TMS-triazoles. Initially, a combination of steric interactions and electronic effects, which lead to an increase of the electrophilicity of the b-carbon of alkynes, was assumed.…”

Asymmetric Synthesis of (R, Z)-(—)-5-(l-Decenyl)oxacyclo-pentan-2-one, the Pheromone of the Japanese Beetle

“…F or the synthesis of the acetylenik keto ester 4, we found that the acylation of 1-trimethylsily-1-decyne 2b with 3 in the presence of aluminum chloride 9 ) gives a reproducible yield of 70%. The starting silylated acetylene 2b could be obtained readily by silylating the lithium salt of 1-decyne 2a.…”