Cavitands as Reaction Vessels and Blocking Groups for Selective Reactions in Water

Masseroni, Daniele; Mosca, Simone; Mower, Matthew P.; Blackmond, Donna G.; Rebek, Julius

doi:10.1002/anie.201602355

Cited by 60 publications

(42 citation statements)

References 18 publications

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“…She also investigates physical and chemical models for the origin of biological homochirality. She has reported on cavitands as reaction vessels and blocking groups for selective reactions in water and on radical C−H functionalization of heteroarenes under electrochemical control in Angewandte Chemie Communcations. Blackmond is currently a member of the Editorial Advisory Board of Advanced Synthesis and Catalysis .…”

Section: Awarded …mentioning

confidence: 84%

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

2019

Angew Chem Int Ed

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Section: Awarded …mentioning

confidence: 84%

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

2019

Angew Chem Int Ed

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“…The use of these cavitands offers the further advantage of providing a vehicle for moving organic reactions into water, providing accelerated rates for water-insoluble substrates. Additional applications of the cavitand in monofunctionalizations (26) and cyclizations to macrolactams (17) and ureas (27) augur well for remote functionalization reactions.…”

Section: Discussionmentioning

confidence: 99%

Water-soluble cavitands promote hydrolyses of long-chain diesters

Shi

Mower

Blackmond

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Water-soluble, deep cavitands serve as chaperones of long-chain diesters for their selective hydrolysis in aqueous solution. The cavitands bind the diesters in rapidly exchanging, folded J-shape conformations that bury the hydrocarbon chain and expose each ester group in turn to the aqueous medium. The acid hydrolyses in the presence of the cavitand result in enhanced yields of monoacid monoester products. Product distributions indicate a two-to fourfold relative decrease in the hydrolysis rate constant of the second ester caused by the confined space in the cavitand. The rate constant for the first acid hydrolysis step is enhanced approximately 10-fold in the presence of the cavitand, compared with control reactions of the molecules in bulk solution. Hydrolysis under basic conditions (saponification) with the cavitand gave >90% yields of the corresponding monoesters. Under basic conditions the cavitand complex of the monoanion precipitates from solution and prevents further reaction.M onofunctionalization of symmetrical compounds poses a general problem: When identical functional groups on a substrate are truly remote, they act independently, and reactions result in a statistical mixture of products. For example, hydrolysis of diesters ( Fig. 1) separated by a long methylene chain exhibits equal rate constants at each site (k 1 = k 2 ), which sets an upper limit of 36.8% for the yield of the monoester. This maximum occurs when comparable amounts of unreacted diester and doubly reacted diacid product are present ( Fig. 1), a factor that often complicates isolation of the desired monoester product.Special circumstances can favor monofunctionalization. When the monofunctionalized compound has fortuitously different properties (such as solubility) and can be removed to a different phase (1) as it is formed, good yields can result. Likewise, when the sites are not remote--as in diesters of oxalic acid--reaction at one site greatly modifies reactivity at the other site and affects the yield of the monofunctionalized product. We describe here the application of synthetic container compounds (cavitands) as molecular chaperones to address the monofunctionalization problem. Whereas the present examples involve only hydrolysis of long-chain diesters, the predictable influence of the cavitand promises wider applications in other reactions of symmetrical, difunctional substrates. Results and DiscussionWe recently reported the synthesis of deep cavitand 1 (Fig. 2) and its capacity to sequester hydrophobic and amphiphilic species in water (2). The eight methyl groups of cavitand 1 broaden its upper rim and prevent dimerization through hydrogen bonding into a capsule. The cavitand is stable over a wide pH range. Whereas a number of water-soluble, deep cavitand hosts are available (3-10), cavitand 1 bound long-chain guest alkanes and related difunctional compounds (bola-amphiphiles) in folded conformations (11). Folded alkyls inside a γ-cyclodextrin were initially characterized by Turro et al. (12), and folded bola-amphiphiles ...

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“…Sie befasst sich überdies mit physikalischen und chemischen Modellen für den Ursprung der biologischen Homochiralität. In Angewandte‐Chemie ‐Zuschriften berichtete sie über Cavitanden als Reaktionsräume und blockierende Gruppen für selektive Reaktionen in Wasser und über die elektrochemisch kontrollierte radikalische C‐H‐Funktionalisierung von Heteroarenen . Blackmond gehört dem Redaktionsbeirat von Advanced Synthesis and Catalysis an.…”

Section: Ausgezeichnet …unclassified

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

2019

Angewandte Chemie

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Cavitands as Reaction Vessels and Blocking Groups for Selective Reactions in Water

Cited by 60 publications

References 18 publications

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

Water-soluble cavitands promote hydrolyses of long-chain diesters

IUPAC 2019 Distinguished Women in Chemistry or Chemical Engineering

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