Dirhodium(II) Tetra(N‐(dodecylbenzenesulfonyl)prolinate) Catalyzed Enantioselective Cyclopropenation of Alkynes.

Abstract

Supporting InformationGeneral Methods: 1 H NMR spectra were run at either 300, 400, or 500 MHz, and 13 C NMR at either 75 or 125 MHz in CDCl 3 unless otherwise noted. Mass spectral determinations were carried out at 70 eV. Melting points were uncorrected. IR spectra were obtained using a Nicolet Impact series 420 IR. Optical rotations were measured using a Jaso DIP-370 digital polarimeter. Glasswares were flame dried prior to use. Solvent hexanes were distilled over sodium with triglyme and benzophenone. Reactions were carried out under an atmosphere of argon. Elemental analysis performed by Atlantic Microlab, Inc.; Norcoss, Georgia. Column chromatography was carried out on Merck silica gel 60 (230-400 mesh). Commercially available reagents were used without additional purification unless noted. Rh 2 (S-DOSP) 4 (1) was prepared by following the literature procedure. 1 General procedure for Rhodium(II)-Catalyzed Decompositions of MethylPhenyldiazoacetate in the Presence of Alkynes: A mixture of alkyne (2.5 -10.0 equiv) and Rh(II) catalyst (0.01 equiv) in 10 mL of hexane was stirred at room temperature under an argon atmosphere. To this solution was added the methyl phenyldiazoacetate (1 equiv, 0.5 mmol) in 5 mL of hexane via syringe pump over 5 h, and the mixture was then

Studies of Asymmetric Styrene Cyclopropanation with a Rhodium(II) Metallopeptide Catalyst Developed with a High‐Throughput Screen

“…For purpose of ee determination, racemic material was generated using Rh 2 (OAc) 4 . The absolute configuration of product 2a is assigned by comparison of the optical rotation to previous reports . The absolute configuration of all other cyclopropane products 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i is assumed by analogy.…”

“…The absolute configuration of product 2a is assigned by comparison of the optical rotation to previous reports. 12,13 The absolute configuration of all other cyclopropane products 2b-2i is assumed by analogy. From our previously published library screening, the 'hit' peptide sequence yielding the highest enantioselectivity in cyclopropanation reaction was found to be the ligand L2.47, and the catalyst Rh 2 (L2.47) 2 -A was prepared according to reported procedures.…”

Gold carbene chemistry from diazo compounds

“…The cycloaddition of alkyne with metal carbene generated from diazo compounds could produce cyclopropenes in a stereoselective manner. Previously, the enantioselective cyclopropenation of terminal alkyne with chiral Rh(II) [47][48][49][50], Co(II) [51] and Ir(III) [52] catalysts has been well established. However, such reaction of internal alkynes was much more challenging.…”

Highly selective synthesis of tetra-substituted furans and cyclopropenes: copper(i)-catalyzed formal cycloadditions of internal aryl alkynes and diazoacetates

“…Alkynes are a valuable class of hydrocarbons for transition metal-catalyzed carbenoid cycloadditions due to their synthetic versatility to undergo highly selective transformations into furans, [1][2][3] indenes, 4 dihydroazulenes, 5 cyclopentadienes, 6,7 and cyclopropene compounds. 5,[8][9][10][11] The diversity of these cycloadducts contain structural features that are found in a wide range of natural products, and therefore, are useful synthetic building blocks in agricultural, pharmaceutical, and material science applications. 12,13 Despite the fact that many metal carbenoid cycloaddition methods are known for terminal alkynes, the lack of synthetic procedures developed for internal alkynes still remains a significant limitation.…”