Generation of Alkyl(dicarbonyl)(chloro)‐ruthenium Dimers in the Ruthenium‐Catalyzed Addition of Alkyl Formates to Ethylene

Abstract

COMMUNICATIONS treated with 2.2 equivalents of 4 (prepared from l-triisopropyl-siIylo~y-3,3-diiodopropane~~~~ and Et,Zn) and 1 equivalent of 3 (Scheme 3). Furthermore, the diastereo-and enantioselectivity for these processes were excellent. [20] In summary, we have developed an expedient and efficient synthesis of enantiomerically enriched 1,2,3-substituted cyclopropanes from allylic alcohols. In addition, we have presented the first cyclopropanation reaction of a functionalized iodoalkylzinc reagent. Applications of this methodology to natural product synthesis is currently underway. Experimental SectionTo a solution of Et,Zn (113 pL, 1.1 mmol) in CH,CI, (5 mL) at 0°C was added CH,CHI, (222 pL, 2.2 mmol) over 5 min. After 10 min of stirring at 0 "C, a solution of the allylic alcohol (0.5 mmol) and (R,R)-dioxaborolane (3) (149 mg, 0.55 mmol) in CH,CI, (2 mL) was added rapidly by cannula. The ice bath was removed, and the reaction was stirred until TLC analysis showed complete consumption of the starting material (1 h). The reaction mixture was then poured into saturated aqueous NH,CI (20mL). and 10% aqueous HCI (10mL) was added. The mixture was extracted three times with ether (10mL). and the combined organic layers were stirred vigorously with 5hl aqueous KOH (15 mL) for 12 h, washed with saturated aqueous Na,SO, (15 mL). with saturated aqueous NH,CI (15 mL), and with saturated aqueous NaCl(15 mL). dried over MgSO,, and concentrated under reduced pressure. The residue was purified by flash chromatography to afford the desired cyclopropane.

A Facile Route to Carbonylhalogenometal Complexes (M = Rh, Ir, Ru, Pt) by Dimethylformamide Decarbonylation

“…IR monitoring of the reaction shows that, after 2 min, the dark-red solution contains a carbonyl species at low concentration since a weak carbonyl band is detected at 2092 cm Ϫ1 . After 2 ] in 70% yield after recrystallization of the crude product from dichloromethane/n-heptane (see Table 1). …”

“…[1Ϫ17] Nevertheless, in some cases, its implication as a reactant has been observed and solvent effects that do not seem to be directly linked with its polarity have been noticed, particularly when the catalytic reaction involves carbon monoxide or further reactions with carbonyl compounds. Thus, in the course of an investigation of the ruthenium-catalyzed hydroesterification of ethylene, the results of which have been reported previously, [1,2] a strong solvent effect was noted. In this reaction, the solvent could be involved in the formation of the active species; in particular, the complex [PPN][RuCl 3 (CO) 2 (DMF)] has been isolated after reaction of the precatalyst [PPN][RuCl 3 (CO) 3 ] with boiling DMF.…”

“…[3] This represents an unusual solvent dependence, particularly as the hydroformylation of alkenes can normally be carried out in almost any solvent. The authors postulated that cotion can occur to provide the complexes [NH 2 (CH 3 2 ]. In the case of platinum, reduction is not effective and [NH 2 (CH 3 ) 2 ][PtCl 3 (CO)] is obtained.…”

Effects of Halides and Related Ligands on Reactions of Carbonylruthenium Complexes (Ru0–RuII)

“…For a long time, these complexes were mainly regarded as intermediates for the preparation of more elaboptimum activity. [60] It was shown that, under the reaction conditions, the alkyl moieties were derived principally from orate species.…”

“…General scheme for the reaction of face-sharing bioctahedral species with nucleophiles 16e Ϫ -acyl species [Ru{C(O)R}(PR 3 ) 2 (CO)Cl] (Scheme 27). [60] If X is an alkenyl group, whether it migrates or not depends on the nature of the starting alkyne. As shown in Scheme 27 [82] It is noteworthy that the same appearing in the scheme denotes a vacant coordination site on the metal center complexes were originally prepared by Ros [83] from RuH(CO)Cl(PR 3 ) 2 .…”