Preparation and regiospecific cyclization of alkenyllithiums

Bailey, William F.; Nurmi, Timo; Patricia, Jeffrey J.; Wang, Wei

doi:10.1021/ja00242a032

Cited by 102 publications

(27 citation statements)

References 4 publications

(7 reference statements)

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“…For example, Bailey and co-workers have reported that the cyclization of 6-hepten-2-yllithium (the secondary alkenyllithium derived from 6-iodo-1-heptene) is apparently complete within a few minutes at -78°C. 29 …”

Section: Resultsmentioning

confidence: 99%

When a very fast radical probe cyclization hints at a carbanionic intermediate rather than at a radical one: a further proof of a polar mechanism for the aryl bromide–alkyllithium exchange reaction

Bodineau¹,

Nudelman²,

García³

et al. 2002

Arkivoc

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Dedicated to Professor Marcial Moreno-Mañas on the occasion of his AbstractA new, very fast aryl radical clock, the 2-bromophenyl 3-phenyl-2-propenyl ether 1, was reacted with n-BuLi in THF. A large amount of cyclized product was formed. Such a product could have arisen from an efficient cyclization of a radical formed by dissociation of the radical anion yielded by an ET to 1. Evolution with time, temperature effects and deuteration results, strongly hint, however, that the mechanism of this exchange reaction is rather of the polar type (S N 2 or "ate complex") in agreement with previous reports from the literature based on evidences gained by other types of approaches. The carbanionic cyclization described here is one of the fastest ever reported.

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Section: Resultsmentioning

confidence: 99%

When a very fast radical probe cyclization hints at a carbanionic intermediate rather than at a radical one: a further proof of a polar mechanism for the aryl bromide–alkyllithium exchange reaction

Bodineau¹,

Nudelman²,

García³

et al. 2002

Arkivoc

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“…The halogen-metal exchange of secondary alkyl iodides leads mainly to hydrocarbons containing Wurtz-type coupling or elimination products [44], except in the case of benzyllithium derivatives which are easily generated from benzyl selenides [45].…”

Section: Five-membered Ring Synthesismentioning

confidence: 99%

Carbometallation Reactions

and¹,

Normant²

1998

Metal‐Catalyzed Cross‐Coupling Reactions

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Carbon-carbon bond formation by means of organometallics was developed mostly after the work of Barbier and Grignard, and has commonly been achieved by their named reactions with polar carbon electrophiles. In the search for new types of selective organometallic carbon-carbon bond formation, and following the pioneering Ziegler addition of some anionic initiators to nonpolarized carbon-carbon bonds [I], controlled carbometallation emerged as a new tool. Since then, reactions which result in the addition of the carbonmetal bond of an organometallic 1 across a carbon-carbon multiple bond 2, leading to a new organometallic 3 in which the newly formed carbon-metal bond can be used for further synthetic transformations (see Scheme 7l), are called carbometallation reactions. 1 2 3 Scheme 7-1 Carbornetallation.To be synthetically useful, the new organometallic 3 must have a reactivity different from that of 1 in order to avoid the polymerization of the carbometallated substrate [2]. So, the carbometallation ability of 1 must be higher than that of 3, except for an intramolecular carbometallation reaction, in which case the entropy factors favor the mono-addition even if the starting organometallic and the product have similar reactivities. Since an outstanding number of additions of organometallics to carbon-carbon multiple bond have been reported and reviewed [3-51, we will focus this chapter on the more recent advances in this field (from 1991 until the present time), both from our own and from other research groups. Carbometallation of Alkynes Intermolecular CarbometallationAlkynes are carbometallated with several organometallic compounds under mild conditions [3] but carbocupration has probably the greatest synthetic possibilities [4], associated with the zirconium-catalyzed methylalumination [5] reaction: both proceed with very high stereoselectivity and afford the syn addition product as described in Scheme 7-2. 1 Metal-catalyzed Cross-coupling ReactionsEdited by François Diederich, Peter J. Stang Scheme 7-2 Carbometallation of alkynes.However, the stereoselectivity of the carbocupration (syn addition) can be inverted by using the 1,2-metallate rearrangement [6], to lead to the organometallic copper species 4 [7] (Scheme 7-3). In every case examined, the stereochemistry of the polysubstituted alkenes formed corresponds to > 99% stereoselectivity. * 1. 2tBuLi. nC~H12 / Et2O 2. Warm to r.t. EtEt 70% Scheme 7-11 Internal carbolithiation of a substituted alkyne.The synthesis of substituted spiro[2.4]heptanes was also recently accomplished by treatment of functionalized iodocyclopropanes as described in Scheme 7-12 [ 161. Carbometallation of Alkynes277 Li OH nBuLi, EtzO -78 "C to r.t. t Me3Si Me3si@ 79% Scheme 7-12 Spirocyclization via carbolithiation.An extension of this intramolecular carbolithiation was recently disclosed for the preparation of bis-exocyclic 1,3-dienes by the 5-exo-dig cyclization of d-acetylenic vinyllithiums. Through subsequent Diels-Alder chemistry, they serve as useful precursors of polycyclic r...

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“…The aldehydes 3 and 4 were converted into their respective iodides 5 and 6 by (i) reduction of the aldehydes with sodium borohydride in ethanol to the corresponding alcohols, (ii) conversion of the alcohols into tosylates, and (iii) displacement of the tosylate moiety by iodide in refluxing acetone. Treatment of iodides 5 and 6 with 2.2 equivalents of terr-butyllithium at -78OC (14), followed by trapping of the resulting carbanion with either acrolein, methacrolein, or crotonaldehyde, provided the allylic alcohols 7-12 in good yield. Alcohols 7 , 8 , 10, and 11 were isolated as mixtures of diastereomers that were not separated, but were oxidized under Swem conditions (15) to provide enones 13, 14, 16, and 17, respectively.…”

Section: Preparation Of Rnonoszrbstit~~ted Imdaf Precursorsmentioning

confidence: 99%

“…The results are summarized in [13][14][15] were less diastereoselective than those of the corresponding precursors 16-18 (diastereoselectivity will refer to the stereocenter on the side chain (i.e., C-2 or C-3)). Only the adducts in which the side chain was orientated syn to the oxygen bridge (at C-6) were detected (by 'H NMR) and isolated.…”

Section: Imdaf Reactions With Florisil In Rnethylene Chloridementioning

confidence: 99%

Diastereoselective intramolecular Diels–Alder reactions of the furan diene: the synthesis of (±)-1,4-epoxycadinane

Rogers¹,

Keay²

1993

Can. J. Chem.

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The diastereoselective intramolecular Diels-Alder reactions of the furan diene (IMDAF), in which the side arm comprises four carbon atoms and is substituted by a methyl group adjacent to, or one carbon removed from, the furan ring, are described. Adducts are formed in moderate to excellent yields when treated with either Florisil in methylene chloride at room temperature or methylaluminum dichloride in methylene chloride at -78°C. Florisil is most effective for substrates containing unsubstituted dienophiles. An equimolar quantity (1.1 equivalents) of methylaluminum dichloride is most effective for precursors having methacrolein-type dienophiles, while a catalytic quantity (0.1 equivalent) is effective for crotonaldehyde-type dienophiles. Only the adducts with the side arm orientated syn with respect to the oxygen bridge are detected and isolated. The major diastereomer is the one in which the methyl group (initially on the side arm) is situated equatorially on the newly formed six-membered ring. An application of the diastereoselective IMDAF reaction to the synthesis of (*)-l,4-epoxycadinane is described, beginning with 2-methylfuran.CHRISTINE ROGERS et BRIAN A. KEAY. Can. J. Chem. 71, 6 1 1 (1993).On dCcrit les reactions diastCrCosClectives de Diels-Alder intramolCculaires du furane (DAIMF) agissant comme diene et dans lequel la chaine laterale comporte quatre atomes de carbone et est substituke par un groupe mCthyle sur le carbone en a ou en p par rapport au noyau furanique. Les addults se forment avec des rendements allant de moyens a excellent~ lorsqu'on les traite soit avec du Florisil dans le chlorure de mCthylkne 2 la tempCrature ambiante soit avec du dichlorure de mCthylaluminium dans le chlorure de mCthylkne a -78°C. Le Florisil est le plus efficace pour les substrats contenant des diknophiles qui ne sont pas substitues. Une quantitC Cquimolaire (1,l equivalents) de dichlorure de mCthylaluminium est le plus efficace pour des diknophiles precurseurs du type mCthacrolCine alors qu'une quantitC catalytique (0,l equivalent) est efficace pour les dienophiles du type crotonaldChyde. On n'a detect6 et isolC que les adduits dont la chaine 1atCrale est orientCe en syrl par rapport au pont oxygCnC. Le diastereoisomkre principal est celui dans lequel le groupe mkthyle (initialement dans la chaine IatCrale) est en position Cquatoriale dans le cycle i six chainons nouvellement forme. On dCcrit une application de la rCaction diastCrCosClective Diels-Alder intramolCculaire du furane pour la synthkse du ( 2 ) -I ,4-6poxycadinane a partir du 2-mCthylfurane. [Traduit par la rCdaction]The intramolecular Diels-Alder reaction of the furan diene (IMDAF) has been studied by many groups since it was fust reported in 1978 (1). These investigations have attempted to define the scope and limitations of the LMDAF reaction with respect to (i) the effect of varying the length of the tether linking the diene and d i e n~~h i l e , ' .~(ii) the effect of substituting heteroatoms for carbon on the t e t h e~-,~.~ (iii) the effect of v...

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Preparation and regiospecific cyclization of alkenyllithiums

Cited by 102 publications

References 4 publications

When a very fast radical probe cyclization hints at a carbanionic intermediate rather than at a radical one: a further proof of a polar mechanism for the aryl bromide–alkyllithium exchange reaction

When a very fast radical probe cyclization hints at a carbanionic intermediate rather than at a radical one: a further proof of a polar mechanism for the aryl bromide–alkyllithium exchange reaction

Carbometallation Reactions

Diastereoselective intramolecular Diels–Alder reactions of the furan diene: the synthesis of (±)-1,4-epoxycadinane

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