Organosubstituierte 1,6‐Dioxa‐2‐sila‐5‐bora‐3‐cycloalkene – Herstellung und Charakterisierung

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Abstract
Organosubstituted 1,6‐Dioxa‐2‐sila‐5‐bora‐3‐cycloalkenes – Preparation and Characterisation1)The cis‐alkenes ROSi(CH3)2C(R)  C(C2H5)B(C2H5)OR (R  CH3: 11; C2H5: 12; C6H5: 13) are prepared from CH3NSI[CH3)2C(R)C(C2H5)BC2H5 [R  CH3: A; R  C(CH3)  CH2: B] with the monohydroxy compounds ROH (R  CH3, C2H5, C6H5). A or B react with aliphatic dihydroxy compounds HOR′OH [R′  CH2CH2: 1; CH(CH3)CH2: 2; CH(CH3)CH(CH3): 3; C(CH3)2C(CH3)2: 4; (CH2)3: 5; (CH2)4: 6] to give 8‐, 9‐, and 10‐membered ring compounds OSi(CH3)2C(R)  C(C2H5)OR′ [15a,b, 16/16′, meso/rac‐17a, D‐17a,b, 18, 19, (20)n]. A is initially cleaved at the SiN bond with formation of 14 Compound 15a crystallises as the 16‐membered (15a)2 [X‐ray structure analysis). The aromatic dihydroxy compounds catechol (7), resorcinol (8), 2,3‐dihydroxynaphthalene (9), 1, 8‐dihydroxynaphthalene (10) react with A to form 21 to 24, but mainly by protolytic BCvinyl fission to give the 2,5‐dihydro‐1,2,3‐dioxaboroles (e.g. 7f1, 9f1, 10f1) and the acyclic boron‐free compounds 7f′3, 9f3, 10f3. The MS and NMR (1H, 11B, 13C, 29Si) data of the new compounds are discussed.