Addition of silylated nucleophiles to α-oxoketenes

Abstract

A general evaluation of silylated nucleophiles to intercept transient α-oxoketenes generated by microwave-assisted Wolff rearrangement of 2-diazo-1,3-dicarbonyl compounds is presented. Original scaffolds and synthetic intermediates are accessed in a rapid, efficient and easy-to-handle way. Mechanistic studies by DFT calculations and some post-functionalizations are discussed.

Experimental and theoretical studies of (4 + 1) annulations between α‐oxoketenes and stable phosphorous, nitrogen, or sulfur ylides

“…This could be evidenced in the case of 4b , the prolonged exposure to air of which resulted in the formation of 4‐bromo‐benzoic acid and furan‐3‐one 2b (Scheme ). Notably, product 2b was previously obtained by a (4 + 1) annulation between the α‐oxoketene derived from diazodimedone and trimethylsilyldiazomethane (Scheme b) …”

“…[4] Using this technique, we have recently examined their reactions with stabilized phosphorous ylides that triggered either standard or abnormal Wittig olefinations of the α-oxoketenes [5] and with trimethylsilyldiazomethane-a nitrogen ylide-that afforded a few furan-3-ones 2 by (4 + 1) annulations followed by hydrolysis (Scheme 1). [6] However, the synthetic value of the latter transformation was limited because it was not possible to introduce efficiently a substituent or a functional group on the one-carbon atom nitrogen ylide cycloaddition partner, for example using ethyl diazoacetate. This prompted us to investigate the reactivity of stable sulfur ylides 3 with α-oxoketenes in order to prepare 3-hydroxyfurans of type 4 through a related (4 + 1) annulation reaction (Scheme 1).…”

“…Notably, product 2b was previously obtained by a (4 + 1) annulation between the α-oxoketene derived from diazodimedone and trimethylsilyldiazomethane (Scheme 1b). [6] Using DFT calculations, we recently disclosed that the standard and abnormal Wittig olefinations of αoxoketenes with carbonyl-stabilized phosphorous ylides are likely to proceed via stabilized betaine intermediates, a peculiarity of α-oxoketenes in Wittig olefinations. [5] In order to get a complete picture of the reactivity of SCHEME 1 Reactivity of α-oxoketenes with phosphorous, nitrogen, and sulfur ylides SCHEME 2 Synthesis of 3-hydroxyfurans 4 α-oxoketenes with phosphorous, nitrogen, and sulfur ylides and also to gain insights on the formation and possible isolation of betaines derived from α-oxoketenes, we embarked in a theoretical mechanistic study using density functional theory (DFT) methods.…”

Time‐Efficient Synthesis of Pyrido­[2,3‐d]pyrimidinones via α‐Oxoket­enes

“…[7] Using this approach, the chemistry of these electrophilic reactive intermediates has been revisited, including their reactions with heteroatom-based, [8] carbon-based, [9] and silylated nucleophiles, [10] N,N-bis-nucleophiles, [11] imines, [12] 1,3-dipoles, [13] and aza-dienes. [7] Using this approach, the chemistry of these electrophilic reactive intermediates has been revisited, including their reactions with heteroatom-based, [8] carbon-based, [9] and silylated nucleophiles, [10] N,N-bis-nucleophiles, [11] imines, [12] 1,3-dipoles, [13] and aza-dienes.…”

“…A few years ago we reported on the microwave-assisted thermal Wolff rearrangement of 2-diazo-1,3-dicarbonyl compounds as an extremely convenient source of α-oxoketenes. [7] Using this approach, the chemistry of these electrophilic reactive intermediates has been revisited, including their reactions with heteroatom-based, [8] carbon-based, [9] and silylated nucleophiles, [10] N,N-bis-nucleophiles, [11] imines, [12] 1,3-dipoles, [13] and aza-dienes. [14] Notably, it was found that electron-rich heterocycles could undergo a Friedel-Crafts-type α-ketoacylation with α-oxoketenes to give the corresponding 1,3-diketones, [9] and that properly functionalized electron-rich heterocycles could undergo cascade reactions initiated by a Friedel-Crafts α-ketoacylation elemental step.…”