Asymmetric intramolecular cyclopropanation of diazo compounds with metallosalen complexes as catalyst: structural tuning of salen ligand
摘要:
Intramolecular cyclopropanation of alkenyl alpha-diazoacetates and alkenyl diazomethyl ketones was examined by using optically active (ON+)Ru(11)(salen) and Co(II)(salen) complexes as catalysts. For the cyclization of 2-alkenyl alpha-diazoacetates, Co(II)(salen) complexes 9 and 10 were found to be superior catalysts to the corresponding (ON+)Ru(11)(salen) complexes 4 and 5. On the other hand, (ON+)Ru(II)(salen) complex 2 was found to be the catalyst of choice for the cyclization of 3-alkenyl diazomethyl ketones, and complex 4 was found to be a good catalyst for the cyclization of (E)-4-alkenyl diazomethyl ketones. The present study demonstrates that metallosalen complexes, especially optically active (ON+)Ru(II)(salen) and Co(11)(salen) complexes, can serve as efficient catalysts for the cyclization of alkenyl diazocarbonyl compounds, if a suitable salen ligand is used as the chiral auxiliary. (C) 2003 Elsevier Science Ltd. All rights reserved.
Asymmetric intramolecular cyclopropanation of diazo compounds with metallosalen complexes as catalyst: structural tuning of salen ligand
摘要:
Intramolecular cyclopropanation of alkenyl alpha-diazoacetates and alkenyl diazomethyl ketones was examined by using optically active (ON+)Ru(11)(salen) and Co(II)(salen) complexes as catalysts. For the cyclization of 2-alkenyl alpha-diazoacetates, Co(II)(salen) complexes 9 and 10 were found to be superior catalysts to the corresponding (ON+)Ru(11)(salen) complexes 4 and 5. On the other hand, (ON+)Ru(II)(salen) complex 2 was found to be the catalyst of choice for the cyclization of 3-alkenyl diazomethyl ketones, and complex 4 was found to be a good catalyst for the cyclization of (E)-4-alkenyl diazomethyl ketones. The present study demonstrates that metallosalen complexes, especially optically active (ON+)Ru(II)(salen) and Co(11)(salen) complexes, can serve as efficient catalysts for the cyclization of alkenyl diazocarbonyl compounds, if a suitable salen ligand is used as the chiral auxiliary. (C) 2003 Elsevier Science Ltd. All rights reserved.
3-oxobutanamides underwent manganese(III)-mediated oxidative intramolecular addition to produce dihydrofuran-fused macrolides and macrocyclic amides from 8 to 26 members. A similar reaction of the oligooxamethylene-tethered ω-alkenyl 3-oxobutanoates also gave dihydrofuran-fused crown ether type macrolides which had a phase-transfer ability with sodium and potassium picrates. The manganese(III)-assisted specific
Synthesis of Bicyclo[3.1.0]hexan-2-ones
by Manganese(III) Oxidation in Ethanol
作者:Hiroshi Nishino、Kentaro Asahi
DOI:10.1055/s-0028-1083324
日期:——
underwent the manganese(III)-induced oxidative intramolecular cyclization in ethanol to produce 3-azabicyclo[3.1.0]hexan-2-ones in good yields. A similar reaction of propenyl 3-oxobutanoates and S-propenyl 3-oxobutanethioates also gave the corresponding 3-oxa- and 3-thiabicyclo[3.1.0]hexan-2-ones. The reaction details, the structure determination, and the reaction pathway are described. cyclizations - oxidations
The reaction of 3,3-diphenyl-2-propenyloxytetramethylene 3-oxobutanoate (14) with manganese(ill) acetate dihydrate in boiling acetic acid caused the oxidative intramolecular radical cyclization to produce 13-methyl-11,11-diphenyl-3,8,12-trioxabicyclo[8.3.0]tridec-13-en-2-one (2(4)) in 94% yield. A similar oxidation of the 3,3-diphenyl-2-propenyloxyoligomethylene 3-oxobutanoates (1(n): n = 2, 3, 6, 8) gave the corresponding macrolides 2(n) (n = 2, 3, 6, 8) in moderate to good yields. A 17-membered crown ether-type macrolide 2, was also obtained in 80% yield by the intramolacular radical cyclization of the oxaethylene-tethered 3-oxobutanoate (11). The structure of the macrolides 2,, (n = 2, 3, 4, 6, 11) has been corroborated by an X-ray crystal structure analysis. (C) 2002 Elsevier Science Ltd. All rights reserved.