One-Pot Cyclizations of (2,4-Dioxobutylidene)phosphoranes and (2-Alkoxy-4-oxobut-2-enylidene)phosphoranes

Abstract

2,4-Dioxobutylidene)phosphoranes and (2-alkoxy-4-oxobut-2-enylidene)phosphoranes are readily available and represent versatile building blocks in one-pot cyclizations. Their reactions with various electrophiles, such as 1,3-dicarbonyl compounds, enones, a-halo ketones, or hydrazine derivatives, allow a convenient synthesis of a variety of carbocyclic and heterocyclic ring systems.

Adventures in the Chemistry of 1,1-Diacylcyclopropanes

“…Silylation of 47 gave silyl enol ether 48 , which was transformed into the 1,3-bis(trimethylsilyloxy)-1,3-butadiene 49 (Scheme 25 ). 42 The cyclization of 49 with silyl enol ether 50 and 1,1,3,3-tetramethoxypropane ( 54 ), following conditions previously developed in our laboratory, 9 10 afforded the expected cyclopropylated salicylates 51 and 55 , respectively. The cyclization of 49 with oxalyl chloride ( 52 ), again following conditions previously developed in our laboratory, 8 afforded cyclopropylated γ-alkylidenebutenolide 53 .…”

“…Based on work of T. H. Chan and co-workers, we studied cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with silyl enol ethers to give salicylates, such as C . 9 In 2002, Gopal Bose – a postdoc from IIT Guwahati (India), developed a cyclization of 2a with 1,1-diacetylcyclopentane to give spirocyclic product D , which can undergo a rearrangement reaction upon treatment with acid. 20 21…”

“…5 We investigated extensively the chemistry of (2,4-dioxobutylidene)phosphoranes 6 and 1,3-bis(silyloxy)-1,3-butadienes 7 as masked dianions. This includes cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride, 8 with other 1,2-dielectrophiles, 5 with 3-silyloxy- and 3-alkoxy-2-en-1-ones, 9 10 with iminium salts, 11 with chromones, 12 and with acid chlorides. 13 Cyclizations of sulfur-, 14 fluorine- 15 and chlorine-containing 16 1,3-bis(trimethylsilyloxy)-1,3-butadienes have been reported.…”

“…We studied cyclizations of free dianions with dielectrophiles, 2 cyclizations of dianions and other dinucleophiles with oxalic acid-bis(imidoyl)dichlorides, 3 cyclizations of oxime and hydrazine dianions, 4 and cyclizations of 1,3-dicarbonyl dianions with 1,2-dielectrophiles to give 2-(alkylidene)tetrahydrofurans. 5 We investigated extensively the chemistry of (2,4-dioxobutylidene)phosphoranes 6 and 1,3-bis(silyloxy)-1,3-butadienes 7 as masked dianions. This includes cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride, 8 with other 1,2-dielectrophiles, 5 with 3-silyloxy- and 3-alkoxy-2-en-1-ones, 9 10 with iminium salts, 11 with chromones, 12 and with acid chlorides.…”

Small and Smart: Adventures in Epihalohydrin Chemistry

“…During the early years of my independent career at the University of Göttingen under the mentorship of Professor Armin de Meijere, I was interested in the development of cyclization reactions of 1,3-dicarbonyl dianions (so-called free dianions) and of 1,3-bis(silyloxy)-1,3-butadienes, which can be represented as electroneutral equivalents of dianions (so-called masked dianions). 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Monoanion A of ethyl acetoacetate ( 2a ) usually undergoes reactions with electrophiles at the central carbon atom of the 1,3-dicarbonyl moiety (Scheme 2 ). In contrast, the employment of dianion B , which can be generated in situ from 2a by treatment with two equivalents of LDA or by sequential addition of sodium hydride and butyllithium, permits functionalization at the terminal carbon atom.…”