Branch‐Selective Intermolecular Hydroacylation: Hydrogen‐Mediated Coupling of Anhydrides to Styrenes and Activated Olefins

Hong, Young‐Taek; Barchuk, Andriy; Krische, Michael J.

doi:10.1002/anie.200602377

Cited by 101 publications

(42 citation statements)

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“…In the event, hydrogenative coupling of vinylarenes to aromatic or a,b-unsaturated carboxylic anhydrides using cationic rhodium catalysts proceeds efficiently [135] (see also [25]). Furthermore, under optimum conditions using triphenylarsine as ligand, complete levels of branch regioselectivity are enforced.…”

Section: Hydrogenative Acyl Substitution (Reductive Hydroacylation)mentioning

confidence: 99%

Hydrogenation for C  C Bond Formation

Bower

Krische

2010

Handbook of Green Chemistry

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The formation of chemical bonds between carbon atoms is of fundamental significance. A major goal in the emerging field of green chemistry involves the design of by-product-free chemical processes, especially CÀC bond-forming processes applicable to renewable feedstocks [1]. This objective is aligned with longstanding economic and aesthetic forces that have shaped the field of chemical synthesis and which have given rise to such concepts as atom-economy [2], step-economy and the ideal synthesis [3]. As revealed by the E-factor (kilogram of waste generated per kilograms of product) [4], it is not surprising that an inverse correlation between process volume and waste generation exists in the chemical industry. For largevolume processes, where minute improvements in efficiency confer significant economic return, by-product-free chemical processes are desirable as they mitigate costs associated with waste disposal and product isolation. Here, fiscal natural selection mandates the practice of green chemistry. In contrast, the fine chemical and pharmaceutical industrial segments often engage in multi-step syntheses where the value of late-stage intermediates can easily exceed the cost of waste stream disposal or product separation, undermining motivation to develop by-product-free protocols (Table 8.1).Must waste production generally increase with increasing molecular complexity? What transformations would be practiced on a vast scale if only efficient by-productfree variants were developed? In the specific case of CÀC bond-forming processes, especially those involving non-stabilized carbanions and their equivalents, a significant cause of waste production resides in the use of stoichiometrically preformed organometallic reagents, which give rise to equimolar quantities of chemical byproducts in the form of metal salts. For example, the vinylation and allylation of carbonyl compounds and imines, which are core reactions in synthetic organic chemistry, uniformly employ preformed vinylmetal and allylmetal reagents. The Green Catalysis, Volume 1: Homogeneous Catalysis. Edited by Robert H. Crabtree

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Section: Hydrogenative Acyl Substitution (Reductive Hydroacylation)mentioning

confidence: 99%

Hydrogenation for C  C Bond Formation

Bower

Krische

2010

Handbook of Green Chemistry

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“…107 Hydrogenation of a mixture of styrenes ArCH=CH 2 (or reactive alkenes, such as norbornene or ethylene) and symmetric or mixed carboxylic anhydrides [(RCO) 2 O or (RCO)O(COR )] in the presence of cationic rhodium catalysts ligated by triphenylarsine (Ph 3 As), generates hydroacylation products ArCH(Me)COR as single regioisomers in high yields. 108 Asymmetric hydroarylation of diphenylphosphinylallenes [Ph 2 P(O)]C(R)=C=CH 2 with arylboronic acids ArB(OH) 2 , catalysed by an Rh-BINAP complex, has been shown to proceed in high yields with high regio-and enantio-selectivity to afford chiral allylphosphine oxides [Ph 2 P(O)]CH(R)C(Ar)=CH 2 of up to 98% ee. A π -allylrhodium ee complex has been identified as the key intermediate.…”

Section: Additions Initiated By Metals and Metal Ions As Electrophilesmentioning

confidence: 99%

Addition Reactions: Polar Addition

Kočovský

2010

Organic Reaction Mechanisms · 2006

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Asymmetric Rh-Catalyzed Intermolecular Hydroacylation of 1,5-Hexadiene with Salicylaldehyde

et al. 2009

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Rh-catalyzed intramolecular [1][2][3][4][5][6][7] and intermolecular hydroacylations [8][9][10][11][12][13][14][15][16][17][18][19] have recently been the focus of synthetic organic and organometallic chemists. Although Rh-catalyzed asymmetric intramolecular hydroacylation (asymmetric cyclization) has been extensively studied by us, [20][21][22][23][24] and other groups, [25][26][27][28] Rh-catalyzed asymmetric intermolecular hydroacylation has attracted only limited attention, 29-31) except for asymmetric hydroformylation. 32,33) This may be because Rh-catalyzed intermolecular hydroacylation did not proceed under mild reaction conditions, but required vigorous reaction conditions. Recently, we have found that Rh-catalyzed intermolecular hydroacylations proceed under mild reaction conditions based on the "double chelation" of aldehyde and diene (Eq. 1).34-37) Here we report enantioselective Rh-catalyzed intermolecular hydroacylation between salicylaldehyde (1) and 1,5-hexadiene (2).(1)The hydroacylation between salicylaldehyde (1) and 1,5-hexadiene (2, 6 eq) using RhCl(PPh 3 ) 3 (0.20 eq) at room temperature afforded a mixture of iso-hydroacylated product 3 and normal-hydroacylated product 3 in the ratio of 4 to 1 in quantitative yield (Eq. 1). The iso-hydroacylated product 3 has a chiral carbon at the a-position. Thus, we envisaged that the asymmetric induction from prochiral 1,5-hexadiene would be possible, if Rh-complex with chiral phosphine ligand were used instead of achiral RhCl(PPh 3 ) 3 .First, we examined the hydroacylation between salicylaldehyde (1) and 1,5-hexadiene (2) using Rh[(R)-BINAP]Cl (0.40 eq) at room temperature. Fortunately, the reaction afforded the mixture of iso-3 and normal-3 in the ratio of 3 to 1, and the specific rotation [a] D of the mixture showed ϩ9.6. This result means that the iso-product is not racemic but optically active, even though the chemical yield was merely 4% (entry 1 in Table 1). This result prompted us to further improve the chemical yield of the product and increase its specific rotation. We increased the amount of Rh-catalyst to 1.0 eq, but the yield of products was not improved. Several additives, such as bases, silver salts, and Lewis acids, were then examined, as shown in Table 1. We thought that the addition of base would deprotonate phenolic protons of salicylaldehyde and promote hydroacylation. In contrast, the addition of silver salt would change the property of Rh-complex to a cationic species to accelerate the reaction. Unfortunately, the addition of bases, such as K 2 CO 3 , KOAc, and NaOAc, did not improve the yield (entries 3-5), and the addition of silver salts, such as AgClO 4 and CF 3 CO 2 Ag, improved the yield of products but their specific rotations were zero, meaning that the products were racemic (entries 6-8). Finally, it was found that the addition of Lewis acid improved the yield of products (entries 9-12); in particular, the addition of Zn(OTf) 2 (0.20 eq) improved the yield of product and its specific rotation showed Ϫ26°(entry 11). However...

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Branch‐Selective Intermolecular Hydroacylation: Hydrogen‐Mediated Coupling of Anhydrides to Styrenes and Activated Olefins

Cited by 101 publications

References 55 publications

Hydrogenation for C  C Bond Formation

Hydrogenation for C  C Bond Formation

Addition Reactions: Polar Addition

Asymmetric Rh-Catalyzed Intermolecular Hydroacylation of 1,5-Hexadiene with Salicylaldehyde

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