No abstract

No abstract

No abstract

Treatment of p-tert-butylcalix[4]arene (C1) and its sulfur-bridged analog T1 with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane in the presence of imidazole gives proximally O,O'-disiloxane-1,3-diyl-bridged calixarenes C2 and T2 in excellent yields, respectively. Subsequent base-catalyzed etherification of the remaining hydroxy groups with alkyl halides gives syn- and anti-O'',O'''-dialkylated products, the stereoselectivity of which varies depending on the nature of the macrocycle, as well as the metal cation of the base employed. Thus, conventional calixarene C2 preferentially affords syn compounds of 1,2-alternate conformation (C3) with the aid of tert-BuOK and K(2)CO(3) and anti counterparts of partial-cone conformation (C4) with Cs(2)CO(3). On the other hand, thiacalixarene T2 affords syn compounds of 1,2-alternate conformation (T3) with any of the bases. The disiloxanediyl bridge of the resulting products can readily be removed by treatment with tetrabutylammonium fluoride. Thus, the net process provides an efficient method for the regio- and stereoselective synthesis of proximally dialkylated calix[4]arenes.

No abstract

No abstract

No abstract

A multifunctional acrylate resin having a tertiary ester structure is synthesized using a thiol‐acrylate Michael addition click reaction. By loading both a photo radical initiator and a photo acid generator into this resin, a positive‐tone photoresist, that can be patterned after photocrosslinking (PPaP), is formulated. After the thin film is irradiated with 365 nm light, radical crosslinking proceeds and a solvent resistant “frozen” film can be obtained. The frozen film works as a positive‐tone photoresist. When the frozen PPaP is irradiated with light containing a wavelength much shorter than 300 nm, the ester structure of the exposed region is decomposed by photo‐chemically generated acid and dissolved in an alkaline solution. Furthermore, a photochemical pattern transfer is achieved using the material. By performing the photo exposure on conventional photoresist patterns on the frozen PPaP underlayer, the photoresist patterns are successfully transferred to the underlayer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45871.