Synthesis of adamantane derivatives. 47. Photochemical synthesis of 4-azahomoadamant-4-enes and further studies on their reactivity in some cycloadditions

Sasaki, Tadashi; Eguchi, Shoji; Toi, Nao

doi:10.1021/jo01335a020

Cited by 26 publications

(8 citation statements)

References 2 publications

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“…On the basis of the above results and previous reports [ 46 , 54 – 59 ], the mechanism of this transformation was described in Figure 5(e) . Initially, the acid-assisted hydroazidation of the C=C double-bond of styrenes occurs to generate the intermediate A with Markovnikov's rule [ 54 , 55 ], which undergoes the subsequent Schmidt-type rearrangement process to afford the imine intermediate B through the cleavage of the C(Ar)-C(alkenyl) single bond [ 46 , 56 – 59 ]. The final hydrolysis of species B produces the desired anilines and aldehyde side products.…”

Section: Resultsmentioning

confidence: 99%

Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

et al. 2020

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As a readily available feedstock, styrene with about 25 million tons of global annual production serves as an important building block and organic synthon for the synthesis of fine chemicals, polystyrene plastics, and elastomers. Thus, in the past decades, many direct transformations of this costless styrene feedstock were disclosed for the preparation of high-value chemicals, which to date, generally performed on the functionalization of styrenes through the allylic C-H bond, C(sp2)-H bond, or the C=C double bond cleavage. However, the dealkenylative functionalization of styrenes via the direct C-C single bond cleavage is so far challenging and still unknown. Herein, we report the novel and efficient C-C amination and hydroxylation reactions of styrenes for the synthesis of valuable aryl amines and phenols via the site-selective C(Ar)-C(alkenyl) single bond cleavage. This chemistry unlocks the new transformation and application of the styrene feedstock and provides an efficient protocol for the late-stage modification of substituted styrenes with the site-directed dealkenylative amination and hydroxylation.

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Section: Resultsmentioning

confidence: 99%

Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

et al. 2020

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“…This hydride migration occurs either in one step or in two steps involving the intermediate 2‐adamantanylnitrene. Imine 7 is readily hydrolyzed during aqueous work‐up to give adamantanone ( 8 ) 11…”

Section: Resultsmentioning

confidence: 99%

Study of the Structure and Photochemical Decomposition of Azidoadamantanes Entrapped in α‐ and β‐Cyclodextrin

et al. 2011

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Photolysis of 1‐azidoadamantane (1), either in its neat state or in alkane solution, yields the dimeric product 4. In contrast, amino alcohol 3 is formed as the sole product in high yield when 1 is confined within cyclodextrins (CyDs). To understand the discrepancy in product distribution caused by supramolecular encapsulation, CyD inclusion complexes (ICs) of azidoadamantanes were fully characterized. Indeed, intermolecular selectivity was influenced by reactant orientation and mobility. Both, 1‐ (1) and 2‐azidoadamantane (5) yield 1:1 ICs with β‐CyD and 1:2 ICs with α‐CyD. As inferred from 2‐D ROESY spectra in D2O, 1 is accommodated at the wider rim of β‐CyD with the azido group pointing into the cavity. However, two principal orientations of 5 inside the cavity of β‐CyD were found. Single crystal X‐ray analysis of solid 5 also demonstrates a bimodal orientation within β‐CyD. In addition, the first induced circular dichroism (ICD) study of an alkyl azide entrapped within CyD cavities is reported. From these data, it was concluded that azide 1 is bound more strongly within β‐CyD in H2O/EtOH = 8:2 at 293 K (Ka = 20240 ± 1000 M–1) than is 2‐azidoadamantane (5) (Ka = 7450 ± 400 M–1).

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“…Though, N ‐fused imidazoles with a saturated aliphatic cycle in 1,5‐position are of great interest as for example Fadrozole ( 3 ), a non‐steroidal aromatase inhibitor used for the treatment of breast cancer, cycloaddition reactions of basic cyclic imines devoid of any additional functionalities have not been explored in the van Leusen imidazole synthesis, except for a cycloaddition reaction with 4‐azahomoadamant‐4‐ene …”

Section: Introductionmentioning

confidence: 99%

Synthesis of 1,5‐Ring‐Fused Imidazoles from Cyclic Imines and TosMIC – Identification of in situ Generated N‐Methyleneformamide as a Catalyst in the van Leusen Imidazole Synthesis

2020

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Imidazoles fused with a cyclic system in 1,5‐position were synthesized via the van Leusen imidazole synthesis employing saturated aliphatic tricycles including an imine function in the base catalyzed cycloaddition reaction with p‐toluenesulfonyl‐methyl isocyanide (TosMIC). Thereby, N‐(tosylmethyl)formamide, a decomposition product of TosMIC, was found to act as a promoter of this reaction leading to considerably reduced reaction times and improved yields. Mechanistic studies revealed that N‐(tosylmethyl)formamide is transformed into N‐methyleneformamide acting as a catalyst in this reaction under the applied basic conditions. Being a Michael acceptor, the employed imines add to this compound, thus being transformed into iminium ions. The so formed intermediates facilitate the first step of the van Leusen imidazole synthesis, which is the addition of deprotonated TosMIC to the iminium subunit. N‐methyleneformamide is finally reformed during the overall reaction and can thus be considered as an organocatalyst of the studied cycloaddition reaction.

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Synthesis of adamantane derivatives. 47. Photochemical synthesis of 4-azahomoadamant-4-enes and further studies on their reactivity in some cycloadditions

Cited by 26 publications

References 2 publications

Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

Study of the Structure and Photochemical Decomposition of Azidoadamantanes Entrapped in α‐ and β‐Cyclodextrin

Synthesis of 1,5‐Ring‐Fused Imidazoles from Cyclic Imines and TosMIC – Identification of in situ Generated N‐Methyleneformamide as a Catalyst in the van Leusen Imidazole Synthesis

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