Reactivite des carbanions benzyliques : VI. Structure et reactivite du trimethylsilyl-9 dihydro-9,10 anthracene; preparation des bis(trimethylsilyl)-9,9 et trimethylsilyl-9 alkyl-9 dihydro-9,10 anthracenes

摘要: Abstract The structure of 9-trimethylsilyl-9,10-dihydroanthracene (Me 3 SiDHA) has been studied by NMR; the coupling constants three 9,10 protons do not change at between 25 and 90°C (ABM spectrum; J AB }- 18.2; AM ⋍ 1.2; BM 0.3 Hz in toluene-d 8 ), indicating that Me Si group prefers quasi axial position. In presence BuLi THF, SiDHA reacts with SiCl to yield new products: 9,9-bis(trimethylsilyl)-9,10-dihydroanthracene (IId) (major), (9,10-dihydroanthracen-9-yl)dimethylsilyl(trimethylsilyl)methane (V) (9-trimethylsilyl-9,10-dihydroanthracen-9-yl)dimethylsilyl(trimethylsilyl)-methane (VI) together known 9,10-bis(trimethylsilyl)-9,10-dihydroanthracene ( cis trans ). carbanion can also be alkylated (alkyl  Me, Et, i-Pr) 9,9-disubstituted derivatives: 9-Me Si-9-alkyl-DHA. formation investigated reveals a competition abstraction base H 9 10 ; latter is less crowded but 9-carbanion stabilized vicinity silicon atom. obtained from exclusively C(9) D 2 O. A study alkylation 9-trimethylsilyl-9-deuterio-9,10-dihydroanthracene shows generation 10-carbanion followed 1,4 hydrogen rearrangement which yields 9-carbanion. mechanism discussed roles t-Bu are compared DHA series.