boron trifluoride diethyl etherate in tetrahydrofuran; diethyl ether T=-78°C;

1: trans-2-butene With n-butyllithium; potassium tert-butylate in tetrahydrofuran; hexane T=-78 - -45°C; Inert atmosphere; 2: With (+)-(Ipc)2B(OMe) in tetrahydrofuran; diethyl ether; hexane T=-78°C; 0.5 h; Inert atmosphere; 3: (E)-crotonaldehyde optical yield given as percent eeFurther stages;

Yield given. Multistep reaction;

aluminium trichloride 1.) ether, -78 deg C, 10 min, 2.) -78 deg C to 0 deg C; Yield given. Multistep reaction. Yields of byproduct given;

chromium dichloride in tetrahydrofuran Ambient temperature; Product distribution;