Conversion of chiral unsaturated cyanohydrins into chiral carba- and heterocycles via ring-closing metathesis
摘要:
Aliphatic unsaturated cyanohydrins 1-3 served as starting materials in the synthesis of a set of new chiral unsaturated cyclic 1,2-ethanolamines. Combining a Grignard addition-NaBH4 reduction sequence with a ring-closing metathesis afforded unsaturated cyclic 1,2-ethanolamines 7-11 and 22-25 in good yields and high ee (96-99%). The conversion of cyanohydrins 1-3 via a DIBAL reduction-transimination-NaBH4 reduction sequence, using allylamine, followed by ring-closing metathesis yielded tetrahydropyridines 28, tetrahydroazepinols 33 and tetrahydroazocinols 34 in high yields and excellent ee (97-99%). (C) 2004 Elsevier Ltd. All rights reserved.
Conversion of chiral unsaturated cyanohydrins into chiral carba- and heterocycles via ring-closing metathesis
摘要:
Aliphatic unsaturated cyanohydrins 1-3 served as starting materials in the synthesis of a set of new chiral unsaturated cyclic 1,2-ethanolamines. Combining a Grignard addition-NaBH4 reduction sequence with a ring-closing metathesis afforded unsaturated cyclic 1,2-ethanolamines 7-11 and 22-25 in good yields and high ee (96-99%). The conversion of cyanohydrins 1-3 via a DIBAL reduction-transimination-NaBH4 reduction sequence, using allylamine, followed by ring-closing metathesis yielded tetrahydropyridines 28, tetrahydroazepinols 33 and tetrahydroazocinols 34 in high yields and excellent ee (97-99%). (C) 2004 Elsevier Ltd. All rights reserved.