Jonathan P. Moerdyk

Diamidocarbenes as versatile and reversible [2 + 1] cycloaddition reagents

We describe the synthesis of a variety of cyclopropanes and epoxides by combining a readily accessible and isolable N,N′-diamidocarbene with a range of structurally and electronically diverse olefins and aldehydes, including electron-rich derivatives. Surprisingly, the cyclopropanation and epoxidation reactions were discovered to be rapid and thermally reversible at relatively low temperatures, two features often desired for applications that utilize dynamic covalent chemistry. In addition, a diamidocyclopropane derivative prepared via this method was hydrolysed successfully to form the corresponding linear carboxylic acid in a metal- and carbon monoxide-free hydrocarboxylation reaction. As such, diamidocarbenes are expected to find utility in the synthesis of cyclopropanes, epoxides and their derivatives, as well as in dynamic covalent chemistry applications. An isolable diamidocarbene is shown to participate in reversible [2+1] cycloadditions with a variety of both electron-deficient and electron-rich olefins and aldehydes. Subsequent hydrolysis of a N,N′-diamidocyclopropane derived from styrene afforded the corresponding linear carboxylic acid, effectively establishing a metal- and carbon monoxide-free, anti-Markovnikov olefin hydrocarboxylation reaction.

N,N′-Diamidocarbenes Facilitate Selective CH Insertions and Transfer Hydrogenations

Over the past several decades, C H activation has emerged as an attractive method for transforming abundant starting materials into valuable products. With the potential to streamline synthetic strategies, increase atom economy, and minimize waste, methods for the selective activation of ubiquitous C H bonds are of intense interest. Carbenes are well positioned for such purposes as C H activation has been a hallmark reaction since an early report by Buchner and Curtius in 1885, though most carbenes capable of these transformations are typically generated in situ and utilize directing transition metals. Isolable carbenes, in comparison, offer the potential for streamlined syntheses of new classes of highly functionalized substrates without byproduct formation. While stable phosphinosilyl, arylamino, aminophosphino, and diaminocarbenes (Figure 1) have

Retracted Article: Homonuclear bond activation using a stable N,N′-diamidocarbene

The activation of molecules possessing homonuclear bonds (i.e., X–X, where X = Br, O, S, or C) using a stable N,N′-diamidocarbene (DAC) is described. Exposing bromine to the DAC at 25 °C afforded a substituted tetrahydropyrimidinium salt in good yield (70%). In contrast, treatment of the DAC with benzoyl peroxide or various disulfides afforded the corresponding diamidoketal or diamidothioketal products, respectively, under mild conditions (25 °C) and in good yield (60–80%). Mechanistic and kinetic studies of the latter reactions were consistent with a concerted process involving the nucleophilic attack of the DAC on the aforementioned substrates. While the diamidoketal decomposed to the corresponding urea (91% yield) at 25 °C, the diamidothioketals produced a thiolate which induced rearrangement to the corresponding ring-opened thioesters (78–90% yield) at elevated temperatures (60 °C). The DAC also inserted into the C(O)–C(O) bond of cyclic and acyclic diones as well as the C(O)–CR bond of a cyclopropenone under mild conditions (25–60 °C); the corresponding products were subsequently isolated in good yield (75–90%).

Dihaloimidazolidinediones as Versatile Halodehydrating Agents

Dihaloimidazolidinediones containing geminal dibromides, dichlorides, or diiodides were synthesized and used to transform various alcohols to their corresponding alkyl halides in high yields and under mild conditions. High functional group tolerance and, in many cases, high selectivities were observed. Efforts toward elucidating the mechanism revealed that significant charge build-up may occur at the eventual halogen containing carbon nucleus prior to substitution.

Architectures of Polymers Synthesized using ROMP

An overview of a wide range of polymeric architectures prepared via ring-opening metathesis polymerization (ROMP) is described with many examples drawn from the past and current literature. The presentation of these materials is organized according to their structural complexity and includes detailed synthetic and characterization information as well as current or potential applications. The chapter concludes with a list of challenges and opportunities for the field.

Erratum: Retraction: Homonuclear bond activation using a stable N,N′-diamidocarbene (Chemical Science (2012) 3 (2986-2992))

Retraction of ‘Homonuclear bond activation using a stable N,N′-diamidocarbene’ by Kelly M. Wiggins et al., Chem. Sci., 2012, 3, 2986–2992.

CCDC 877776: Experimental Crystal Structure Determination

Related Article: Young-Gi Lee, Jonathan P. Moerdyk and Christopher W. Bielawski|2012|J.Phys.Org.Chem.|25|1027|doi:10.1002/poc.3004