Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• propargylamines by nucleophilic addition. The synthesis of propargylamines by diastereoselective reductive amination requires alkynyl ketones, which are difficult to prepare and are unstable towards reductive conditions. In approach I, organometallic nucleophiles are added to N-sulfinyl propargylimines, derived

Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• -acyloxyalkynyl ketones were efficiently converted into highly substituted furans with 2.5 mol % of triflimide (triphenylphosphine)gold(I) as a catalyst in dichloroethane at 70 °C. Keywords: alkynyl ketones; cycloisomerization; furans; gold-catalysis; 1,2-migration; Introduction Furans are an important class of

• ], alkynes and sulfur ylides [18][19], alkynyl oxiranes [20][21][22][23][24][25][26], alkynyl ketones [27][28][29][30][31][32][33][34][35], alkynyl alcohols [36][37][38][39][40][41][42][43][44][45][46], and alkynyl ethers [47][48]. Very recently, a three-component coupling reaction toward furans catalyzed by

• ) within 1–46 h [31][52][53]. Despite the relative harsh reaction conditions, furans could be obtained in good to excellent yields. However, one major limitation was ascribed to the types of the employed ketones (R3 in Scheme 2), as only phenyl and tert-butyl alkynyl ketones were able to furnish acceptable

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• organocuprates with alkynyl ketones or esters have been well established [14][34][35][36][37], alkynes bearing an electron-withdrawing group other than carbonyl have been investigated recently [25][38]. The Xie, Marek, and Tanaka groups have been interested in copper-catalyzed carbometalation of sulfur-atom

• ][51][52][53] or enolates [54] from simple alkynes by carbocupration reactions. Not only copper but also rhodium can catalyze carbometalation reactions. Hayashi applied carborhodation chemistry [55][56][57][58] to the reactions of aryl alkynyl ketones with arylzinc reagents, which provided enolates of

• allylmagnesiation of alkynyl sulfone. Copper-catalyzed four-component reaction of alkynyl sulfoxide with alkylzinc reagent, diiodomethane, and benzaldehyde. Rhodium-catalyzed reaction of aryl alkynyl ketones with arylzinc reagents. Allylmagnesiation of propargyl alcohol, which provides the anti-addition product

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• the intermediacy of α,β-alkynyl ketones in the four-component process could not be confirmed (TLC). In addition, their reaction with hydrazines was shown to be ineffective under the present solvent system in the presence or absence of palladium catalyst. This may suggest that if α,β-alkynyl ketones

Construction of cyclic enones via gold-catalyzed oxygen transfer reactions

• Leping Liu,
• Bo Xu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2011, 7, 606–614, doi:10.3762/bjoc.7.71

• cyclic enones from alkynyl ketones Yamamoto and co-workers were the first to report the gold-catalyzed formation of conjugated cyclic enones under mild conditions using tethered alkynyl ketones as substrates (Scheme 2) [43]. Both, aromatic and aliphatic groups substituted on alkynyl ketones 1 were

• produced β,γ-unsaturated bicyclic enones rather than their α,β-unsaturated counterparts. Yamamoto and co-workers proposed a [2 + 2] mechanism for their gold-catalyzed cyclization of alkynyl ketones (Scheme 3). In their mechanism, the carbonyl group attacks the gold activated triple bond to form an oxonium

• and the final product 4. The isolated intermediate 5 could be transformed into a mixture of 6 and 4 under the reaction conditions, finally yielding 4 via intramolecular aldol condensation. This gold-catalyzed cyclization of alkynyl ketones to enones was successfully utilized in a cascade reaction by