Nickel-Catalyzed Three-Component [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes

Transcription

1 Nickel-Catalyzed Three-Component [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes Selective Synthesis of Multisubstituted Cycloheptadienes 1 2 Cat. Ni Komagawa, S.; Saito, S. Angew. Chem., Int. Ed. Engl. 2006, 45, 2446 Michel Grenon April 1 st, 2006 Michel Wipf Group 1 4/3/2006

2 Presentation utline ther Transition-tal Catalyzed Cycloadditions for the Construction of Seven-mbered ings [6+1] Cycloaddition of arenes with!-diazo carbonyl compounds [5+2] Cycloaddition of vinylcyclopropanes with alkynes [4+3] Cycloaddition of dienes with TMM derivatives Previous Examples of Transition-tal Catalyzed(diated) [3+3+2] Cycloadditions for the Construction of Seven-mbered ings Iridium-mediated allyl/alkyne [3+2+2] cycloaddition Cobalt-mediated allyl/alkyne [3+2+2] cycloaddition Nickel and hodium-catalyzed [3+2+2] cycloaddition of alkenyl Fischer carbene complexes and allenes Nickel-Catalyzed Intermolecular [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes Future Work Ye, T.; McKervey, M. A. Chem. ev. 1994, 94, 1091 Michel Wipf Group 2 4/3/2006

3 Transition-tal Catalyzed [6+1] Cycloaddition (Buchner eaction) N 2 Et, h! von E. Doering, W.; Laber, G.; Vonderwahl,.; Chamberlain, N. F.; Williams,. B. J. Am. Chem. Soc. 1956, 78, 5448 (excess) N 2 Et h( 2 CCF 3 ) 2, rt 100% Anciaux, A. J.; Demonceau, A.; Noels, A. F.; Hubert, A. J.; Warin,.; Teyssie, P. J. rg. Chem. 1981, 46, 873 Substituted arenes give mixtures of isomeric products h(ac) 2, rt CH 2 Cl 2 95% N 2 McKervey, M. A.; Tuladhar, S. M.; Twohig, M. F. J. Chem. Soc., Chem. Commun. 1984, 129 Ye, T.; McKervey, M. A. Chem. ev. 1994, 94, 1091 Michel Wipf Group 3 4/3/2006

4 Transition-tal Catalyzed [5+2] Cycloaddition Formation of a metallacycle, followed by a straindriven cleavage of the cycloprane ring and a reductive elimination to the cycloheptadiene An increase in reaction rate is also observed when the reactions are performed in CF 3 CH 2 H Wender, P. A.; Takahashi, H.; Witulski, B. J. Am. Chem. Soc. 1995, 117, 4720 Lautens, M.; Klute, W.; Tam, W. Chem. ev. 1996, 96, 49 Michel Wipf Group 4 4/3/2006

5 Transition-tal Catalyzed [4+3] Cycloaddition Ac Pd(PPh 3 ) 4 (7 mol%) 2 C C 2 dppe (1.5 mol%) Dioxane,!, 8 h 98% 2 C 2 C C C 2 Trost, B. M.; Nanninga, T. N.; Chan, D. M. T. rganometallics 1982, 1, 1543 C 2 CH 2 CH 2 Ph Ac Pd(Ac) 2 (5 mol%) P(iPr) 3 (35 mol%) THF,!, 8 h 88% C 2 CH 2 CH 2 Ph Minor amounts of [3+2] cycloadduct observed Freezing the diene in a cisoid conformation favors the formation of the seven-membered ring Trost, B. M.; MacPherson, D. T. J. Am. Chem. Soc. 1987, 109, 3483 Lautens, M.; Klute, W.; Tam, W. Chem. ev. 1996, 96, 49 Michel Wipf Group 5 4/3/2006

6 Previous Examples of [3+2+2] Cycloadditions Iridium-mediated allyl/alkyne [3+2+2] cycloaddition *Cp Ir Tf Ph Ph CH 2 Cl 2, 0 C to rt, 24 h 56% *Cp Ph Ir Ph Tf Ph *Cp Ir Tf *Cp " Ir Tf CH 2 Cl 2, 0 C to rt, 24 h ca. 40% (3:1) Ph ' Similar results with phenylacetylene ', " =, Ph *Cp Ir Tf CH 2 Cl 2, 0 C to rt, 12 h 78% Cp* Ir Tf Stoichiometric reaction, and poor selectivities are obtained for unsymmetrical alkynes Schwiebert, K. E.; Stryker, J. M. J. Am. Chem. Soc. 1995, 117, 8275 Michel Wipf Group 6 4/3/2006

7 Previous Examples of [3+2+2] Cycloadditions Cobalt-mediated allyl/alkyne [3+2+2] cycloaddition Dramatic solvent effect (THF affords cyclopentadienyl complexes) Conditions: CH 2 Cl 2, excess alkyne (3 to 10 equiv.), 78 C to rt, 12 h Nucleophilic alkylation (Na-dimethylmalonate) of 3, followed by an oxidative decomplexation using [Cp 2 Fe] + Tf affords substituted cycloheptadienes Etkin, N.; Dzwiniel, T. L.; Schweibert, K. E.; Stryker, J. M. J. Am. Chem. Soc. 1998, 120, 9702 Michel Wipf Group 7 4/3/2006

8 Previous Examples of [3+2+2] Cycloadditions Nickel and hodium-catalyzed [3+2+2] cycloaddition of alkenyl Fischer carbene complexes and allenes eaction affords the [3+2] cycloadduct when performed in toluene Least substituted C=C bond of the allene inserts (head-to-head allene allene coupling) Done with Ni(cod) 2 Barluenga, J.; Vicente,.; Barrio, P.; Lopez, L. A.; Tomas, M.; Borge, J. J. Am. Chem. Soc. 2004, 126, Michel Wipf Group 8 4/3/2006

9 Previous Examples of [3+2+2] Cycloadditions Nickel and hodium-catalyzed [3+2+2] cycloaddition of alkenyl Fischer carbene complexes and allenes Least substituted C=C bond of the allene inserts (head-to-tail allene allene coupling) eversible metalla-[4+2] cycloaddition gives IV, which evolves to the more stable V Done with [h(cod)cl] 2 Barluenga, J.; Vicente,.; Barrio, P.; Lopez, L. A.; Tomas, M.; Borge, J. J. Am. Chem. Soc. 2004, 126, Michel Wipf Group 9 4/3/2006

10 Nickel-Catalyzed Intermolecular [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes Good results obtained with sterically hindered terminal alkynes (entries 1 9) ther phosphines [P(Bu) 3, P(Cy) 3, P(t-Bu) 3, dppe] were less effective ther catalysts [hcl(pph 3 ) 3, CpCo(PPh 3 ) 2, CpCp(C) 2 ] were not effective Saito, S.; Masuda, M.; Komagawa, S. J. Am. Chem. Soc. 2004, 126, Michel Wipf Group 10 4/3/2006

11 Nickel-Catalyzed Three-Component [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes Selective Synthesis of Multisubstituted Cycloheptadienes 1 2 Cat. Ni Komagawa, S.; Saito, S. Angew. Chem., Int. Ed. Engl. 2006, 45, 2446 Michel Grenon April 1 st, 2006 Michel Wipf Group 11 4/3/2006

12 Nickel-Catalyzed Intermolecular [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes (4 equiv.) (1 equiv.) Ni(cod) 2 (10 mol%) PPh 3 (20 mol%) Toluene, rt, dropwise addition of reagents Entry Yield (%) 1 CH TBDMSCH PhCH n-c 6 H Ph 56 6 p-c 6 H p-cf 3 C 6 H H(CH 3 ) 2 C 69 DMF can also be used, but not THF, Et 2 or CH 2 Cl 2 Terminal alkyne doesn't need to be bulky in order to get good regioselectivities (see different groups) ther alkynes; (4 equiv.) (4 equiv.) (4 equiv.) (4 equiv.) TBDMS BDMS t-bu Pr Pr Komagawa, S.; Saito, S. Angew. Chem., Int. Ed. Engl. 2006, 45, 2446 Michel Wipf Group 12 4/3/2006

13 Nickel-Catalyzed Intermolecular [3+2+2] Cocyclization of Ethyl Cyclopropylideneacetate and Alkynes Ni more sterically congested Et 2 C Ni 0 Ni path a Ni path b Ni cyclopropylmethyl!butenyl rearrangement Komagawa, S.; Saito, S. Angew. Chem., Int. Ed. Engl. 2006, 45, 2446 Michel Wipf Group 13 4/3/2006

14 Future Work Extend this reaction to other cyclopropylmethylene derivatives Et 2 C Et? ' Extend this reaction to cyclobutylmethylene derivatives Et? (Feasible? Beilstein search resulted in no hits.) Attempt to apply this methodology to the synthesis of complex natural products Ye, T.; McKervey, M. A. Chem. ev. 1994, 94, 1091 Michel Wipf Group 14 4/3/2006