Study on Reactions of Alkynyl Compounds Containing Cyclopentyl Group Induced by Ruthenium Complexes
Date Issued
2014
Date
2014
Author(s)
Lee, Cheng-Yuan
Abstract
Abstract
Treatment of propargyl alcohol 1 with [Ru]-Cl ([Ru] = CpRu(PPh3)2) in the presence of KPF6 and K2CO3 in CH2Cl2 affords the acetylide complex 2. The dehydration takes place at CδH and CγOH, instead of at CβH and CγOH. Then, protonation of 2 with HBF4 in ether produces the vinylidene complex 3. Formation of 1,3-enyne 5 directly from 1 is catalyzed by 30 mol % of [Ru]NCMe+PF6－ in MeOH at 60oC or indirectly from 3 by stirring the solution in CH3CN/CHCl3 for 12 h. Alkylation of 2 by allyl bromide as an alkylation reagent results in formation of vinylidene complex 4. Intramolecular cyclization of 6a and 6b each containing a hydroxyl group with [Ru]-Cl in the presence of NH4PF6 in CH2Cl2 for 12 h afford oxacyclic carbene complexes 7a and 7b, respectively. However, treatment of 6a and 6b with 10 mol% of [Ru]-Cl in n-BuNH2 at 90oC for 12 h affords the dihydrofuran and dihydropyran products 8a and 8b, respectively.
Epoxidation reaction adds an oxygen atom across the double bond of 5 to yield 1-alkynyloxirane 9. Reaction of 9 with [Ru]-Cl in the presence of KPF6 in MeOH affords the spiro-oxacyclic carbene complex 10. Rearrangement of 9 with a Lewis acid, BF3‧Et2O, affords α-alkynylketone 11 via a ring-expansion process of the cyclopentyl group. Treatment of 11 with [Ru]-Cl in different alcohols in the presence of KPF6 at room temperature affords the fused oxabicyclic carbene complex 12 via intramolecular cyclization reaction. However, in the presence of NH4PF6 in CH2Cl2, the same reaction affords 10 via cascade cyclization/ring-contraction.
When 1,6-enyne 14a is treated with 1 mole equiv. of [Ru]-Cl in the presence of NH4PF6 in CH2Cl2 at room temperature for 24 h, complex 15, the six-membered oxacyclic product 16a, and an aldehyde molecule 17 in a ratio of 1:2:1 are isolated. However, in the presence of KF in MeOH for 12 h, instead of NH4PF6 in CH2Cl2, only 2 is obtained. Three analogous compounds 14b, 14c, and 14d are prepared similarly, using different ketones as staring materials. Furthermore, the reaction of 14a-14d with 20 mol% of [Ru]-Cl in the presence of NH4PF6 in CH2Cl2 at 40oC for 12 h affords six-membered oxacyclic 16a-16d in better yield. In addition, structures of complexes 7a, 10 and 12a’ are confirmed by X-ray diffraction analysis.
Subjects
釕金屬
乙炔基
亞乙烯基
碳烯
環戊烷
開環反應
重排反應
縮環反應
環化反應
Type
thesis
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