Recent Advances in the Pauson–Khand Reaction and Related [2+2+1] Cycloadditions

Brummond, Kay M.; Kent, Joseph L.

doi:10.1016/s0040-4020(00)00148-4

Cited by 523 publications

(138 citation statements)

References 107 publications

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“…This is usually achieved by converting the hydroxyl group to a metal alkoxide. [23][24][25][26] Various other useful methods employing transition metals have been reported [27][28][29][30][31][32][33][34][35][36][37][38] ; however, these methods have limited applicability. To achieve one-pot etherification, the following four processes need to be performed: i) consider the alcohol as an electrophile and activate the hydroxyl group, ii) generate a carbocation, iii) consider the alcohol as a nucleophile and form an ether, and iv) control further reactions that lead to fission of the newly formed C-O bond.…”

Section: Regular Articlementioning

confidence: 99%

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

Ohta

Koketsu

Nagase

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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Results of screening of other etherification conditions using 1a are shown in Table 1. Various metals, mainly lanthanoids, were found to be effective for etherifications in MeNO 2 -H 2 O. Next, we selected propargyl alcohols bearing other aromatic substituents as starting materials and performed etherifications under the suitable condition using Sc(OTf) 3 /MeNO 2 -H 2 O at 30°C. With the Sn(OTf) 2 system, the product 2aa was also obtained in the satisfactory yield, however, a small amount of unknown compounds were contaminated. Results of these comparisons are shown in Table 1.Using the same substrate, 3-p-methoxyphenylpropargyl alcohol 1a, etherification with 1°alcohols including methanol, dodecanol and geraniol as nucleophiles produced products 2ab, 2ac and 2af, respectively, in good yields (entries 1, 2

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Section: Regular Articlementioning

confidence: 99%

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

Ohta

Koketsu

Nagase

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…[1] In particular, catalytic intramolecular PK reactions of enynes have received considerable attention to date, owing to their synthetic importance for giving the bicycloalkenone framework. [2] Furthermore, rhodiumcatalyzed PK reactions that utilize aldehydes as CO sources have been developed recently to avoid the direct use of harmful CO gas. [3] In this context, we envisioned that an alternative catalytic intramolecular PK-type reaction without the direct use of CO gas would be realized using squaric acid (SA) 1 as a platform (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Convergent Synthesis of Azabicycloalkenones using Squaric Acid as Platform

et al. 2006

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“…9,10) of enynes (alkyne-alkene). [11][12][13][14][15][16][17] Furthermore, the PKTR of the bis(allene) s 1 (n=1,2) has become a powerful tool for constructing not only the bicyclo[5.3.0]-decadienones 2 (n=1), but also the larger-sized bicyclo[6.3.0]-undecadienone skeletons 2 (n=2) in satisfactory to high yields [18][19][20] (Chart 1). This ring-closing reaction has exclusively occurred at both terminal double bonds of the allenic moieties of 1 (n=1, 2).…”

mentioning

confidence: 99%

Rh(I)-Catalyzed Intramolecular Carbonylative [2+2+1] Cycloaddition Reaction: Preparation of Bicyclo[5.3.0]decadienones with Substituted Cyclopentenone Frameworks

Mukai

Takahashi

Ogawa

et al. 2014

CHEMICAL & PHARMACEUTICAL BULLETIN

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The [RhCl(CO) 2 ] 2 -catalyzed [2 2 1] cycloaddition of bis(allene)s, which have a substituent at the allenic terminus, produced the 8-substituted bicyclo[5.3.0]deca-1(10),6-dien-9-one frameworks. The synthesis of 8,10-dimethylbicyclo[5.3.0]deca-1(10),6-dien-9-one could also be achieved from the bis(1,1,3-trisubstitutedallene). 9,10) of enynes (alkyne-alkene). [11][12][13][14][15][16][17] Furthermore, the PKTR of the bis(allene) s 1 (n=1,2) has become a powerful tool for constructing not only the bicyclo[5.3.0]-decadienones 2 (n=1), but also the larger-sized bicyclo[6.3.0]-undecadienone skeletons 2 (n=2) in satisfactory to high yields [18][19][20] (Chart 1). This ring-closing reaction has exclusively occurred at both terminal double bonds of the allenic moieties of 1 (n=1, 2). We have now investigated the application of this Rh(I)-catalyzed PKTR to the tri-and tetrasubstituted bis(allene) s 3 (R 1 =substituent, R 2 and/or R 3 =H or substituent)to determine its scope and limitations. Results and DiscussionOur initial evaluation for the Rh(I)-catalyzed PKTR was carried out using bis(allene) 5a, which has a methyl group at one of the two allenic termini (Table 1). According to the conditions previously reported for the PKTR of substrates 1, a solution of 5a in toluene was heated at 80°C for 12 h in the presence of 5 mol% [RhCl(CO) dppp] 2 under an atmosphere of CO to afford the desired 8-methylbicyclo[5.3.0] decadienone 6a (dr= 3 : 2) in 38% yield (entry 1). An increase in the loading amounts of [RhCl(CO) dppp] 2 from 5 to 10 mol% provided 6a (dr= 1 : 1) in a lower yield (27%, entry 2). Another catalyst, [RhCl(CO) 2 ] 2 (5 or 10 mol%), also gave the ring-closed products 6a (dr= 1 : 1) in rather low yields (13% or 18%, entries 3, 4). A significant improvement (6a, dr= 1 : 1, 90%) was observed when the ring-closing reaction was carried out in the presence of 5 mol% [RhCl(CO) 2 ] 2 under a higher CO atmosphere (5 atm) (entry 5).21) The formation of 6a can be rationalized in terms of the intermediacy of the 8-methylbicyclo[5.3.0] deca-1,6-dien-9-one derivative 6a′, the β,γ-unsaturated ketone moiety of which should immediately isomerize to the α,β-unsaturated one.We next investigated the [RhCl(CO) 2 ] 2 -catalyzed PKTR of several bis(allene) species 5b-f having trisubstituted-allenyl/ disubstituted-allenyl moieties under 5 atm CO. These results are summarized in Table 2. The bis(allene) s 5b and c, having a heteroatom on the alkyl tether, consistently produced the corresponding bicyclic compounds 6b, c in good yields

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Recent Advances in the Pauson–Khand Reaction and Related [2+2+1] Cycloadditions

Cited by 523 publications

References 107 publications

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

Convergent Synthesis of Azabicycloalkenones using Squaric Acid as Platform

Rh(I)-Catalyzed Intramolecular Carbonylative [2+2+1] Cycloaddition Reaction: Preparation of Bicyclo[5.3.0]decadienones with Substituted Cyclopentenone Frameworks

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