Cycloaddition Reactions of Iodonium Ylides of Cyclic β-Diketones with 1,3-Dienes: Evidence for a Stepwise Mechanism

Abstract

The irradiation of a cyclic b-dicarbonyl iodonium ylide with 1,3-diene in acetonitrile gives substituted dihydrofurans in moderate to high yields, presumably via a stepwise mechanism.Iodonium ylides 1 are considered as synthetic equivalents of the corresponding diazo compounds, without major drawbacks such as explosion, toxicity, and/or carcinogenicity. Furthermore, b-dicarbonyl and b-disulfonyl iodonium ylides are readily prepared 2,3 in high yields from the related active methylene compounds and a hypervalent iodine precursor. The photochemical and/or metal-catalyzed decomposition of these stable iodonium ylides generated reactive intermediates, which undergo several types of reactions, i.e. transylidation 1 with various nucleophiles, cycloaddition reactions leading either to the formation of cyclopropanes 3,4 or five-membered heterocycles 5 , etc.Following our studies directed towards the development of new synthetic applications of iodonium ylides 6 , we thought that heavily substituted dihydrofurans could be easily obtained by the reaction of a b-dicarbonyl iodonium ylide and a conjugated diene. The use of 1,3-diene has been emerging from the point of view that an extra double bond moiety in the dihydrofuran could lead to further interesting transformations, as well as that the presence of this extra olefinic moiety should influence the behaviour of the reacting double bond. We have previously published 6a,d the synthesis of dihydrofurans starting from iodonium ylide 1a and alkenes. Based on these results, we now wish to report the synthesis of 1,5-dienes 3 by the reaction of iodonium ylides 1a,b with 1,3-dienes 2.Irradiation of a suspension of iodonium ylide 1a, and 1,3-diene 2a in CH 3 CN for 60 min at room temperature afforded 7 dihydrofuran 8 3a in 83% yield (Scheme 1). The reaction was extended to iodonium ylide 1b and a variety of 1,3-dienes 2b-f, which underwent facile cycloadditions, affording the related dihydrofurans 3 in moderate to excellent yields (Table). When the reactions were repeated thermally, in the presence of catalytic amounts of Cu(acac) 2 , complex mixtures of inseparable products were isolated instead.It is noteworthy that the reaction proceeds without the use of an inert atmosphere. Acyclic 2a-d, with varied degree Scheme 1Downloaded by: University of Arizona Library. Copyrighted material.

Αντιδράσεις Των Ιωδο Υλιδίων Β-Δισουλφονών Και Β-Δικετονών

“…Ç Rh II -êáτáëυüìåíη êυêëοπñοóθÞêη του υëéäßου τηò äéìåäüíηò 2, êáθþò êáé äéÜöοñωí áíáëüãωí áυτÞò, ÷ñηóéìοποéÞθηêáí ãéá τη óύíθåóη οîáaeοëþí 39, äéϋäñοöουñáíßωí 40, êáé äéϋäñοοîåπéíþí 41 (Ó÷Þìá 28). [85][86][87][88] Ïìοßωò, η Rh II -êáτáëυüìåíη êυêëοπñοóθÞêη του υëéäßου τηò äéìåäüíηò 2 ìå öουñÜíéο οäηãåß óτο áíáìåíüìåíο τñéêυêëéêü πñοúüí 42 ìå êáëÝò áποäüóåéò (Ó÷Þìá 29). 89 [163][164][165] Áπüóπáóη του éωäοâåíaeοëßου áπü το éωäéíÜíéο Â, áποìÜêñυíóη äéοîåéäßου του θåßου, êáé åπáíáöοñÜ τηò áñωìáτéêüτητáò ìÝóω ìåτÜθåóηò πñωτοíßου οäηãåß τåëéêÜ óτο ëηöθÝí πñοúüí 132δ.…”

“…85 Áîßaeåé íá óηìåéωθåß üτé η äñáóτéêüτητá του éωäο υëéäßου ìå τá äéÝíéá áêοëουθåß τη óåéñÜ 1,2-äéϋποêáτåóτηìÝíοò äéπëüò äåóìüò (1,2-ÄÄÄ) < ìοíοϋποêáτåóτηìÝíοò äéπëüò äåóìüò (ÌÄÄ) < 1,1-äéϋποêáτåóτηìÝíοò äéπëüò äåóìüò (1,1-ÄÄÄ). Πéθáíüτáτá, οé ÌÄÄ êáé οé 1,1-ÄÄÄ áíτéäñούí τá÷ύτåñá áπü τοí 1,2-ÄÄÄ ëüãω Ýëëåéøηò óτåñåο÷ηìéêÞò Ç Ýíäåéîη üτé τá éωäο υëßäéá áíτéäñούí πáñουóßá êáτáëυτéêÞò ποóüτητáò óυìπëüêωí του Rh(II) ìÝóω ó÷ηìáτéóìού τωí áíτßóτοé÷ωí êáñâåíßωí (Þ êáñâåíοåéäþí) êáθéåñþθηêå ãéá τηí πåñßπτωóη του PhI=C(CO 2 Me) 2 32 êáé Üëëωí áíÜëοãωí éωäο υëéäßωí.Ôá πñοúüíτá 53 που πñοêύπτουí áπü τηí Rh II êáτáëυüìåíη áíτßäñáóη åßτå τωí éωäο υëéäßωí, åßτå τωí áíÜëοãωí äéáaeωåíþóåωí ìå óτυñÝíéο, áëëυëο âåíaeüëéο êáé öáéíυëο áêåτυëÝíéο, åßíáé áêñéâþò τá ßäéá (Ó÷Þìá 36) 88,89,[93][94][95].…”

“…58,76 Óå üëåò áυτÝò τéò πåñéπτþóåéò Ýãéíå ÷ñÞóη êáτÜëëηëωí υποêáτåóτηìÝíωí öáéíοëþí, ούτωò þóτå íá οäηãηθούí áπåυθåßáò óτéò åπéθυìητÝò âåíaeοöουñáíéêÝò åíþóåéò. Åíτούτοéò, τá áñ÷éêÜ υëßäéá τωí öáéíοëþí áυτþí óυíτßθåíτáé ìå ÷áìηëÝò áποäüóåéò, πåñßπου 40-45%, åíþ τá πñοúüíτá τωí áíτéäñÜóåωí êυêëοπñοóθÞêηò ìåτáîύ τωí éωäο υëéäßωí öáéíοëþí ìå äéÜöοñá äéποëáñüöéëá, üπωò áëêÝíéá, áëêßíéá êáé öουñÜíéá, πñοêύπτουí óå áñêåτÜ ÷áìηëÝò áποäüóåéò (Ó÷Þìá 113).óυíτßθåíτáé ìå ìåãÜëåò áποäüóåéò êáé áíτéäñούí ποóοτéêÜ ìå äéÜöοñá äéποëáñüöéëá, οäηãþíτáò óτá πñοúüíτá êυêëοπñοóθÞêηò [85][86][87][88][89]239. Ôá πñοúüíτá êυêëοπñοóθÞêηò ìποñούí åí óυíå÷åßá íá áñωìáτοποéηθούí ìå áíτéäñáóτÞñéá, üπωò åßíáé η äéêυáíο äé÷ëωñο âåíaeοêéíüíη (DDQ),240 το âñωìéού÷ο ëßθéο-áíθñáêéêü ëßθéο,241 êáθþò êáé το ìοñéáêü éþäéο 242.…”

“…Ç 1,3-êυêëοåîáíοäéüíη 159α êáé η 1,3êυêëοπåíτáíοäéüíη 159â öÝñουí åíåñãÝò ìåθυëåíéêÝò οìÜäåò êáé ìå êáτåñãáóßá ìå PhI(OAc) 2 äßíουí τá áíτßóτοé÷á υëßäéá ìå êáëÝò áποäüóåéò. ÓυãêåêñéìÝíá το υëßäéο τηò 1,3-êυêëοåîáíοäéüíηò 158α Þτáí Þäη ãíωóτü óτη âéâëéοãñáößá85,88,239 êáé óυíτßθåτáé óύìöωíá ìå το ó÷Þìá 115, åíþ το υëßäéο τηò êυêëοπåíτáíοäéüíηò 158â óυíτÝθηêå óτο åñãáóτÞñéο óύìöωíá ìå το ó÷Þìá 116. Óτηí åéêüíá 11, áπåéêοíßaeåτáé η áêτßíá × του Áπü το ó÷Þìá 116 öáßíåτáé üτé ο ó÷ηìáτéóìüò του υëéäßου 158â πñáãìáτοποéÞθηêå áπουóßá âÜóηò.…”

“…Áπü τá πéο åêτåíþò ìåëåτηìÝíá éωäο υëßäéá óτη âéâëéοãñáößá åßíáé το éωäο υëßäéο τηò äéìåäüíηò 2 78,[85][86][87]. Èá áíáìÝíáìå, ëοéπüí, το éωäο υëßäéο 158α íá åìöáíßaeåé πáñüìοéá óυìπåñéöοñÜ.…”