Tatsuo Toyoda

Aminohaloborane in organic synthesis. VI. A simple enantioselective aldol synthesis

Abstract A simple asymmetric aldol condensation of acetophenone and benzaldehydes was performed via chiral vinylaminodichloroborane. The enatioselectivity was compared with that by a similar method using magnesium and lithium.

Aminohaloborane in Organic Synthesis. IV.1 A Directed Aldol Condensation Using Vinylaminodichloroborane

Abstract Continuing our studies on the specific ortho substitution reaction of anilines,2 we tried to extend this methodology to directed aldol condensation3. Namely, N-cyclohexylidencyclohexylamine 1 was treated with boron trichloride and triethylamine in dichloromethane giving N-cyclohexyl-N-1-cyclohexenylaminodi-chloroborane 2, to our knowledge, a new type of aminohaloborane. Similar treatment of N-2-butyliden-cyclohexylamine 3 gave N-cyclohexyl-N-2-butenylamino-dichloroborane (a mixture of E and Z isomers) 4. The physical data satisfied the assigned structures.

Aminohaloborane in Organic Synthesis. V.1 An Aldol-Type Condensation of Acetonitrile and Phenylacetonitrile with Benzaldehydes Using Secondary Aminodichloroborane

Abstract 3-Phenyl-3-sec-aminopropionitriles (1) are not found in literature. We describe here a simple synthesis of 1 from acetonitriles (2) and benzaldehydes (3) using sec-aminodichloroboranes (4)2 and triethylamine (5).

Aminohaloborane in organic synthesis. VIII. A one-step synthesis of 2-Aminobenzhydrols from anilines

Abstract 2-Aminobenzhydrols were obtained regiospecifically from anilines and benzaldehydes with the aid of phenyldichloroborane and triethylamine via N-anilinophenylchloroborane.

Aminohaloborane in Organic Synthesis. VII.1A Directed Aldol Condensation Using Vinyloxyaminochloroborane

Abstract Vinyloxydichloroboranes (1) are scarcely found in literature2 probably because of certain unstable properties. We have found that some vinyloxyamino-chloroboranes (2), which can be prepared by formal substitution of one chlorine atom of 1 with a diethylamino group, are isolable stable compounds.