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The synthesis and reactivity of polysilylacetylenes: Diels—Alder reactions to give bis (silyl) benzenes
Author(s) -
Jones Paul Ronald,
Albanesi Todd E,
Gillespie Ralph D,
Jones Priscilla C,
Ng Seik Weng
Publication year - 1987
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.590010605
Subject(s) - chemistry , chlorosilane , silylation , reactivity (psychology) , cycloaddition , alkoxy group , medicinal chemistry , adduct , hydrolysis , acetylide , organic chemistry , alkyl , silicon , catalysis , medicine , alternative medicine , pathology
Six bis(silyl)acetylenes (XMe 2 SiCCSiMe 2 X) with the following varied silicon substituents X were prepared: 1 (Me, Me); 2 (H, H); 3 (C1, H); 4 (CI, CI); 5 (MeO, H); 6 (MeO, MeO). While 1 and 2 may be prepared by the reaction of dilithio‐ or bis(bromomagnesium)‐acetylide with the appropriate chlorosilane, similar reactions designed to give 3–6 yielded oligomers, XMe 2 Si(CCSiMe 2 ) n X, 7, X=CI, MeO, as the major products, indicating that the acetylenic functionality on silicon activates the chlorosilane towards nucleophilic substitution. Compounds 3 and 4 were prepared by free radical chlorination of 2. Methanolysis of 3 and 4 gave quantitative yields of 5 and 6 respectively. Compounds 1–6 undergo a Diels–Alder reaction with α‐pyrone to produce, after loss of carbon dioxide, bis(silyl)‐substituted benzene derivatives. The order of reactivity has been determined to be: 4=6>3=5>1>2, indicating that chloro or alkoxy substituents favor the cycloaddition with 2‐ pyrone. The adducts formed by compounds 3–6 undergo an unusually facile hydrolysis or elimination to give 1,1,3,3‐tetramethyl‐1,3‐disila‐2‐oxaindane.