Ethyloboration of selenium dioxide and selenium bis(terr-butylimide) molecular structure of an orgaeo-substituted eight-membered t-boseo-2 heterocycle111

Article abstract of DOI:10.1002/cber.19961290506

Both selenium dioxide (1) and selenium bis(feri-butylimide) (2) react with triethylborane (A) by 1, 2-ethyloboration. In the case of 1, ethane, ethene., diethylselane (4a), tetraethyldiboroxane (Et₂B)₂O (B), triethylboroxine (EtBO)3 (D) and a cyclic compound [-Et₂BOSe(Et)O-]₂ (52) are formed after heating to 65 °C. Compound 52 is also formed when 1 reacts with B. Treatment of selenous acid (3) with A or, preferentially for synthetic purposes, with B provides further routes to 5₂. The reaction of the diimide 2 with A starts already below -50°C: a cyclic ethaneselenic acid derivative 6, Et₂EN(tBu)-Se(Et)N(Bu, is formed, and 6 starts to decompose at -50°C by elimination of ethene to give finally (feri-butylamino)diethylborane (8), bis(diethylboryl)-terf-butylamine (9), and Et₂Se (4a). Transborylation of 52 with (9-BBN)₂O (C) affords [-(9-BBN)OSe(Et)O-]₂ (10₂), which crystallizes in the monoclinic space group P21/n with the lattice constants (118 K) a= 667.1(1), b= 1282.5(1), c= 1289.1(1) pm and = 93.06(1). All reactions were monitored by ¹¹B- and ⁷⁷SeNMR spectroscopy. Furthermore, the reactions of 1 with A and B and the transborylations were studied by ¹⁷O-NMR spectroscopy using the 17O-enriched compounds 1(¹⁷O), B(¹⁷O), C(¹⁷O), andD(¹⁷O). VCH Verlagsgesellschaft mbH, , 1996.