An Exploratory Study of Silylated Amino Boronic Ester Chemistry

✍ Scribed by Donald S. Matteson; Rajendra P. Singh; Christopher H. Sutton; James D. Verheyden; Jian-hui Lu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 207 KB
• Volume: 8
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/(sici)1098-1071(1997)8:6<487::aid-hc5>3.0.co;2-4

✦ Synopsis

Diisopropyl

[bis(trimethylsilylamino)methyl]boronate, the analogous pinacol boronic ester (3), and pinacol [(2,2,5,5-tetramethyl-2,5,1-disilazol-1-yl)methyl]boronate (8) were prepared from the corresponding (bromomethyl)boronic ester 1 or 2 and silylated lithium amide. Reaction of 3 or 8 with (dichloromethyl)lithium yielded the corresponding [1chloro-2-(silylated amino)ethyl]boronate 4 or 9. Further transformations of 4 to methylthio derivative 5 and dimethylamino derivative 7 as well as conversion of 5 to ureido derivatives 6 are described. (S,S)-1,2-Dicyclohexylethanediol [1-chloro-2-(trityloxy)ethyl]boronate (13) has been converted to bis(trimethylsilyl)amino derivative 14 and formamido derivative 15 as well as to N-benzyl analogs 18 and 19. Attempted chain extensions of 14, silylated 15, or 19 with (dichloromethyl)lithium indicated that the alkyl migration from boron to carbon is slow and incomplete.