Synthese von tricyclischen 2,3‐Dihydro‐1 H ‐1,3‐stannaborolen

Synthesis of Tricyclic 2,3‐Dihydro‐1 H ‐1,3‐stannaboroles A weak intramolecular interaction between a strongly basic amino group (SnNEt 2 ) and a trigonal atom suffices to deprotonate a BCH group and to eliminate amine. This is shown by organoboration of (diethylamino)dimethyl‐1‐propynylstannane ( 1 ) using 9‐alkyl‐9‐borabicyclo[3.3.1]nonanes [alkyl Me ( 5a ), Et ( 5b ), i Pr ( 5c )]. In the first step, the heterocycles 6a, b are formed. These eliminate diethylamine upon heating to give the new tricyclic 2,3‐dihydro‐1 H ‐1,3‐stannaborole derivatives 7a, b . In the case of 7c , the intermediate 6c was not observed. 1 H‐, 11 B‐, 13 C‐, and 119 Sn‐NMR data are reported.