A novel, highly selective photocyclic aromatization (SCAT) of π-conjugated polymers from phenylacetylene having two hydroxyl groups to exclusively yield a 1,3,5-trisubstituted benzene derivative was developed, and its success was confirmed by (1)H NMR, GPC, and TOF-MS. The SCAT reaction has many unique characteristics. (1) It is a quantitative reaction: it gave only the corresponding cyclic trimer, i.e., a 1,3,5-trisubstituted benzene derivative, quantitatively (100%). No byproducts were produced under the best conditions. (2) It is an intramolecular reaction: it occurred between three adjacent monomer units in one macromolecule. (3) It is a stereospecific and topochemical or template reaction: the reactivity strongly depended on the configuration and conformation of the starting polymer substrates. (4) It is a photoreaction: high selectivity (100%) was observed only by the use of visible light irradiation, not by heating. (5) It is a solid-state reaction: high selectivity (100%) was observed only in the solid state, not in solution. In addition, (6) the resulting cyclic trimers could form a self-supporting membrane, despite their low molecular weights. This new approach resulted in a new class of supramolecular polymers consisting of a 1,3,5-trisubstituted benzene derivative, numbers of which were linearly linked by hydrogen bonds and stacked benzene derivatives. Since SCAT has such high selectivities and is useful for the preparation of a self-supporting supramolecular polymer membrane, many applications can be expected.

The polymer nitrile N-oxide containing poly(ethylene glycol) (PEG) skeleton PEG-CNO was synthesized via a stepwise reaction.

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A new synthetic route for obtaining polyfunctional nitrile N-oxides from OH-tethering nitrile N-oxide is reported.

Mono-, di-, and trifunctional kinetically stabilized aliphatic nitrile N-oxides were synthesized via a two-step process comprising an initial nucleophilic addition of a heteroatomtethering and a carbon-centered nucleophile to a nitroethene and subsequent dehydration of the resultant nitroalkane. We further present the first X-ray crystal structure investigation of an aliphatic nitrile N-oxide. The kinetics of the products' click reactions and DFT calculations confirmed that the obtained nitrile N-oxides had high reactivities.Keywords: Click reaction | Aliphatic nitrile N-oxide | Kinetic studyClick reactions represented by Cu(I)-catalyzed Huisgen dipolar cycloaddition of azides and alkynes (CuAAC) have recently become an essential protocol in synthesis fields based on molecular integration.1 To date, although various improvements have already been achieved, 2 the explosiveness of azides, in addition to the requirement of a Cu catalyst, still causes serious limitations to this type of reaction. Meanwhile, nitrile N-oxides possess a significant potential because they are highly reactive 1,3-dipoles, which allows them to undergo a catalystfree [2+3] cycloaddition reaction with not only alkynes but also alkenes and nitriles to yield the corresponding nitrogencontaining heterocycles.3 Nitrile N-oxide is mostly used as an in-situ-formed reactive species owing to its fast oligomerization. 4 Meanwhile, we have reported the synthesis of kinetically stabilized nitrile N-oxides by introducing bulky substituents, which has enabled very efficient click reactions like end-cap reactions for interlocked molecule synthesis, 5 polyaddition, 6 polymer modifications, 7 and crosslinking reactions. 8 We have employed two effective synthetic methods, namely dehydrohalogenation of hydroxamoyl halide 5,6,7a,8 and one-pot synthesis via conjugate addition of carbanion to nitroethene followed by dehydration, 7b,7c to obtain aromatic nitrile N-oxides mainly. However, because aromatic nitrile N-oxides have a strong tendency to thermally isomerize to their corresponding isocyanates, 9 we were interested in the significant potential of using stable aliphatic nitrile N-oxides 7b,7c,10 as click reagents. Since click reactions using nitrile N-oxides have many benefits such as the ability for CC bond formations, catalyst-free reaction conditions, and availability of versatile dipolarophiles in addition to being very safe, the development of stable aliphatic nitrile N-oxides and their synthesis method should greatly advance the field of click chemistry. Mukaiyama's method is quite suitable for this purpose because it utilizes the dehydration of a primary nitroalkane precursor, 11 which was easily provided via the conjugate addition of several nucleophiles to nitroethene derivatives, to give reactive nitrile N-oxides in excellent conversion. In fact, various nitrogen-containing heterocycles have already been synthesized using this method.12 However, Mukaiyama's method has never been applied for the synthesis of stable aliphatic nitrile N-oxides ...