Hydroformylation/allylation

In almost the same manner frans-disubstituted hydrooxepans can be obtained from a tandem hydroformylation/allyl boration of (-E)-alkoxyallyl-boronates as a mixture of anomers (Scheme 24) [79]. 

To also add an application to aromatic compounds we cite the Heck-hydroformylation sequence [57] (see 121) and to extend these directed additions into the silicon and boron field a regioselective silylformylation-allyl silylation sequence [58] and a hydroformylation-allyl boration hydroformylation cascade are included. 

The hydroformylation-allylation sequence was also used by Leighton for the synthesis of the aldehyde segment (Scheme 2.157). The formation of bis-allyl silyl ether 175... 

Started out from alcohol 174, obtained by an anft-selective crotylation. Deprotonation of the alcohol with butyl lithium and transformation with HSiClj were directly followed by treatment with allyl magnesium bromide to generate the bis-allyl silane 175. The subsequent hydroformylation-allylation process followed by oxidative work-up established tetraol 176 with three iyn-configured alcohols. Protection of two OH groups as the acetonide allowed to conduct the mercury-induced hydroformylation step. As described in the... 

Ma.nufa.cture. Most butanediol is manufactured in Reppe plants via hydrogenation of butynediol. Recendy an alternative route involving acetoxyiation of butadiene has come on stream and, more recendy, a route based upon hydroformylation of allyl alcohol. Woddwide butanediol capacity has climbed steadily for many years. In 1990 it was estimated to be 428,000 metric tons (141), as compared to a Htde more than 70,000 metric tons in 1975... 

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. 

Diastereoselective hydroformylation can be achieved in special cases through passive substrate control in which conformational preferences are transferred in the corresponding selectivity-determining hydrometalation step [4-6]. A recent example is the highly diastereoselective hydroformylation of a kainic acid derivative (Scheme 17) [64], The selective formation of the major diastereomer has been explained via a reactive substrate conformation in which allylic 1,2-strain has been minimized. In this situation the czs-positioned methylene carbonylmethoxy group controls the catalyst attack to occur from the si face exclusively. 

Thus, [HRh(C0)(TPPTS)3]/H20/silica (TPPTS = sodium salt of tri(m-sulfophenyl)phopshine) catalyzes the hydroformylation of heavy and functionalized olefins,118-122 the selective hydrogenation of a,/3-unsaturated aldehydes,84 and the asymmetric hydrogenation of 2-(6 -methoxy-2 -naphthyl)acrylic add (a precursor of naproxen).123,124 More recently, this methodology was tested for the palladium-catalyzed Trost Tsuji (allylic substitution) and Heck (olefin arylation) reactions.125-127... 

Selectivity refers to the fraction of raw material alkene that is converted to product aldehyde, but since hydroformylation typically gives both a linear and branched isomer, selectivity also refers to the relative amounts of each. The linear branched (l b) ratio is highly catalyst dependant. One must simultaneously consider whether the proposed catalyst will give the desired l b selectivity and also whether the proposed catalyst is feasible for use with the catalyst/product separation technologies. For example, water extraction of a polar product, such as in the hydroformylation of allyl alcohol to give 4-hydroxybutanal, would not work well with a sodium salt of a sulfonated phosphine since both are water soluble. 

The desired product in the hydroformylation of allyl alcohol is 4-hydroxybutanal. As with other alkenes, hydro formylation gives both a linear and a branched isomer (Equation 2.1). 

Another route to the diol monomer is provided by hydroformylation of allyl alcohol or allyl acetate. Allyl acetate can be produced easily by the palladium-catalyzed oxidation of propylene in the presence of acetic acid in a process similar to commercial vinyl acetate production. Both cobalt-and rhodium-catalyzed hydroformylations have received much attention in recent patent literature (83-86). Hydroformylation with cobalt carbonyl at 140°C and 180-200 atm H2/CO (83) gave a mixture of three aldehydes in 85-99% total yield. 

Allyl alcohol may be a preferred olefin for rhodium hydroformylation routes to 1,4-butanediol. Comparison of allyl acetate and allyl alcohol as... 

Cobalt hydroformylation of butadiene produced low yields (24%) of an equimolar mixture of n- and isovaleraldehyde (40). It has been established that the cobalt hydrocarbonyl adds to form a stable 7r-allyl complex (93, 94). 

Hydrofoil impellers, 16 673—674 Hydroformulation, 13 768 Hydroformylation, 10 598 allyl alcohol, 2 236—237 ionic liquids in, 26 882—885 maleic anhydride, 15 492 metal carbonyls in, 16 72—73 rhodium-catalyzed, 19 647 Hydroformylation reactions, 13 448 Hydrogasification, coal, 13 845 Hydrogel-based drug delivery,... 

The hydroformylation of unsaturated nitriles such as crotonitrile and allyl cyanide is a potential route towards chiral amino alcohols, which are building blocks in the synthesis of pharmaceuticals. The hydroformylation of acrylonitrile was studied in the early years [5], but lately the hydroformylation of allyl cyanide and crotonitrile have also been investigated [25,81]. 

The asymmetric hydroformylation of allyl cyanide has recently focused the interest of researchers because the iso-aldehyde derivative can be easily transformed into 2-methyl-4-aminobutanol, a useful building block, for instance for the asymmetric synthesis of tachikinin (58), a novel NK1 receptor agonist developed by Takeda [82], It should be noticed that this aldehyde is not accessible via the hydroformylation of crotononitrile. 

Table 5 Rh-catalyzed asymmetric hydroformylation of allyl cyanide with ligands 2, 5, 59-62 ...

Abstract Aldehydes obtained from olefins under hydroformylation conditions can be converted to more complex reaction products in one-pot reaction sequences. These involve heterofunctionalization of aldehydes to form acetals, aminals, imines and enamines, including reduction products of the latter in an overall hydroaminomethylation. Furthermore, numerous conversions of oxo aldehydes with additional C.C-bond formation are conceivable such as aldol reactions, allylations, carbonyl olefinations, ene reactions and electrophilic aromatic substitutions, including Fischer indole syntheses. 

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