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1 1999

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Katalityczne hydroborowanie

Meller Jerzy, Zaidlewicz Marek

Wiadomości Chemiczne

1999

[Z] 53, 11-12

787-809

Catalytic hydroboration a rapidly expanding branch of hydroboration reaction, is reviewed. Catecholborane is the hydroborating agent most often used in catalytic hydroboration. Rhodium, iridium, ruthenium, palladium and other transition metal compounds, including lanthanide iodides, are used as catalysts. The mechanism of catalytic hydroboration is discussed and schemes showing the catalytic action of Wilkinson's catalyst and lanthanide complexes are presented. The reactivity of alkenes in catalytic hydroboration decreases with the increasing substitution of the double bond. Generally, regioselectivities of the catalyzed and uncatalyzed hydroboration of terminal alkenes and alkynes are similar, the boron atom being placed preferentially at the terminal position. The catalyzed reaction makes possible higher selectivity by proper choice of the catalyst. However, the catalytic hydroboration of styrene and its derivatives may be directed to from preferentially the Markovnikov type addition products. Stereoselectivities of the catalyzed and incatalyzed hydroboration of allylic and homoallylic derivatives are often opposite. The catalytic monohydroboration of conjugated dienes and enynes provides the 1,2- and 1,4-additon products depending on the catalyst. Enantioselective catalytic hydroboration of prochiral olefins is described and selected reactions providing hydroboration to the synthesis of natural products are given.