Synthesis of 2,2,5,5‐Tetrasubstituted 1,4‐Dioxa‐2,5‐disilacyclohexanes via Organotin(IV)‐Catalyzed Transesterification of (Acetoxymethyl)alkoxysilanes

Abstract

(Acetoxymethyl)silanes 2, 7a-c, and 10a-c with at least one alkoxy group, of the general formula (AcOCH2 )Si(OR)3-n(CH3)n (R: Me, Et, iPr; n=0, 1, 2), were synthesized from the corresponding (chloromethyl)silanes 1, 6a-c, and 9a-c by treatment with potassium acetate under phase-transfer-catalysis conditions. These compounds were found to provide 2,2,5,5-organo-substituted 1,4-dioxa-2,5-disilacyclohexanes 3, 8a-c, and 11a-c if treated with organotin(IV) catalysts such as dioctyltin oxide. The reaction proceeds through transesterification of the acetoxy and alkoxy units followed by ring-closure to form a dimeric six-membered ring. The corresponding alkyl acetates are formed as the reaction by-products. With these mild conditions, the method overcomes the drawbacks of previously reported synthetic routes to furnish 2,2,5,5-tetramethyl-1,4-dioxa-2,5-disilacyclohexane (3) and even allows the synthesis of 1,4-dioxa-2,5-disilacyclohexanes bearing hydrolytically labile alkoxy substituents at the silicon atom in good yields and high purity. These new materials were fully characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and X-ray analysis (trans-8a).

Molecular Dumbbell, Sandwich, and Paddle-Wheel Assembled with Methylresorcin[4]arene Cavitands and Organooxotin Clusters

“…Organooxotin clusters have attracted considerable attention owing to their remarkable structure diversity, − catalytic ability in organic reactions, and potential biocidal activity. − So far, several organooxotin clusters, such as ladder, , drum, cube, football cage, cyclic trimer, butterfly, and o-capped, have been synthesized and their structures characterized by single-crystal X-ray diffraction analysis. The organooxotin clusters can be chemically modified by organic ligands with carefully selective spacers or tailed groups .…”

Fast Strategy to Functional Paper Surfaces

“…Because of the general reactivity of the trichlorosilane group to various functional groups, for example, organic and inorganic hydroxyl groups, amino groups, and carboxyl groups, ,, our method can be applied on many types of commercial available paper substrates. To prove this, TCVS treatment was applied on a copy paper (containing inorganic fillers such as TiO 2 ), “Post it” paper (containing dyes), tracing paper, and toner paper (containing a conductive toner covering layer), the obtained vinyl paper substrates were further modified with FDT or ME, and the contact angle of the modified paper (water, DCM and EtOH) were recorded.…”

“…Combination of the TCVS treatment and thiol−ene modification can lead to a highly efficient modification method, which can convert a bare cellulose paper to almost any functional paper in 10 min, much faster than most reported strategies for chemical functionalization of the paper (3−12 h). 1,31,44,45 Because of the general reactivity of the trichlorosilane group to various functional groups, for example, organic and inorganic hydroxyl groups, amino groups, and carboxyl groups, 43,46,47 our method can be applied on many types of commercial available paper substrates. To prove this, TCVS treatment was applied on a copy paper (containing inorganic fillers such as TiO 2 ), "Post it" paper (containing dyes), tracing paper, and toner paper (containing a conductive toner covering layer), the obtained vinyl paper substrates were further modified with FDT or ME, and the contact angle of the modified paper (water, DCM and EtOH) were recorded.…”

Preise der Gesellschaft Deutscher Chemiker: K. Müllen, A. Fürstner, L. F. Nazar, M. Scheer, T. C. Schmidt, R. E. Mulvey, B. Rieger, H. L. Anderson, A. Llobet

“…Zu den Forschungsthemen von Rieger und seiner Forschungsgruppe zählen polymere organische und Hybridmaterialien, auf Silicium basierende Produkte, die Katalyse und die chemische Umwandlung von Kohlenstoffoxiden. In Chemistry—A European Journal erschienen Arbeiten von ihm über durch Organozinn(IV)‐Verbindungen katalysierte Veresterungen6a und die Funktionalisierung Metall‐organischer Gerüste 6b. Rieger gehört dem International Advisory Board von Macromolecular Chemistry and Physics an…”