Hydroformylation reactions epoxides

The preceding stoichiometric reactions are clearly closely related to the catalytic hydroformylation of epoxides. Somewhat less clear is their relation... 

The phosphorous analogue of 2,2 -bis(3-t-butylsalicylideamino)-l,T-binaphthyl prepared, (II), and used in asymmetric hydroformylation reactions (1). Manganese analogues of (II) have been prepared and behave as asymmetrically epoxidizing agents in the presence of idosobenzene (2). 

The oxygen attachment and development of heterobimetallic complexes bearing the M—O—M motif is a successful strategy for the design of catalysts for olefin epoxidation and olefin hydroformylation reactions. 

Macromolecular metal complexes with modified poly(ethylene oxide)s have also been applied as catalysts for asymmetric reactions epoxidation, dihydroxy-lation, hydrogenation, and hydroformylation. 

Scheme 6.104 Mechanism of the cobalt-catalyzed hydroformylation of epoxides and the isomerization as a typical side reaction [6].

Some rhodium catalysts for hydroformylation of epoxides have been claimed by Union Carbide and Shell (Scheme 6.106) [17]. By the use of phosphites (e.g., Alkanox 240, BIPHEPHOS) or phosphine-modified rhodium catalysts, the selectivity was enhanced and the reaction temperature could be lowered. Noteworthy, occasionally a higher partial pressure of Hg in the syngas mixture with a total pressure of 90 bar was employed. 

Dimerization of the formed cx,P-hydroxy aldehyde may become a serious issue in the hydroformylation of epoxides with acidic metal catalysts. Orchin s group observed chiefly self-acetallzatlon products in the stoichiometric ring-opening reaction of cyclohexene oxide with CO and HCo(CO) (Scheme 6.108) [23]. 

Polyols of a given triglyceride prepared via epoxidation and hydroformylation reactions are illustrated in Figure 22.20. The hydroformylation allows the introduction of an extra carbon per double bond. Additionally, the primary OH groups... 

Many organic chemical transformations have been carried out in ionic liquids hydrogenation [4, 5], oxidation [6], epoxidation [7], and hydroformylation [8] reactions, for example. In addition to these processes, numerous synthetic routes involve a carbon-carbon (C-C) bond-forming step. As a result, many C-C bondforming procedures have been studied in ambient-temperature ionic liquids. Among those reported are the Friedel-Crafts acylation [9] and allcylation [10] reactions, allylation reactions [11, 12], the Diels-Alder reaction [13], the Heck reaction [14], and the Suzuld [15] and Trost-Tsuji coupling [16] reactions. 

The carbonyl complex [Ru(EDTAH)(CO)] has been reported to be a very good catalyst for reactions like hydroformylation of alkenes, carbonylation of ammonia and ammines as well as a very active catalyst for the water gas shift reaction. The nitrosyl [Ru(EDTA)(NO)] is an oxygen-transfer agent for the oxidation of hex-l-ene to hexan-2-one, and cyclohexane to the corresponding epoxide. 

Silylformylation, defined as the addition of RsSi- and -CHO across various types of bonds using a silane R3SiH, CO, and a transition metal catalyst, was discovered by Murai and co-workers, who developed the Co2(CO)8-catalyzed silylformylation of aldehydes, epoxides, and cyclic ethers [26]. More recently, as described in detail in Section 5.3.1, below, alkynes and alkenes have been successfully developed as silylformylation substrates. These reactions represent a powerful variation on hydroformylation, in that a C-Si bond is produced instead of a C-H bond. Given that C-Si groups are subject to, among other reactions, oxidation to C-OH groups, silylformylation could represent an oxidative carbonylation of the type described in Scheme 5.1. 

Promising results were observed in Friedel-Crafts alkylation77 and epoxidation.78 Higher rates or better selectivities were found for hydroformylations in supercritical C02.79-84 Simple trialkyl phosphines, for examples, were shown to provide highly active Rh catalysts.81 Hydroboration showed enhanced regioselec-tivity.85 The Wacker reaction performed in alcohol-supercritical C02 exhibits high reaction rates and markedly increased selectivity toward methyl ketone.86... 

The isomerization of epoxides is discussed in Section II, D,l. The isomerizations of olefins and of alkyl- and acylcobalt carbonyls have been considered as side reactions to hydroformylation but studies dealing principally with these reactions will now receive attention. 

Similarly, preparation of a,a-difluorohomoallylic alcohols has been achieved by zinc-mediated addition of CH2=CHCF2Br to carbonyl compounds.29 The reaction is successful with dialkyl ketones as well as aliphatic and aromatic aldehydes (Equation 4.12). The allylation products are particularly useful since the alkene may be oxidized to an aldehyde,32 epoxide,33 or converted to a 8-lactone34 via hydroformylation. 

Draw structures of ligands derived from the chiral framework of glucose, tartaric acid, binaphthol, and cinchona alkaloids that are used for efficient asymmetric hydrocyanation, epoxidation, hydroformylation, and alkene dihydroxylation reactions respectively. 

Hydroformylation, see also Oxo reaction, of epoxides, 63 of glycals, 86 of olefins, 61... 

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