The C2 Selective Nucleophilic Substitution Reactions of 2,3-Epoxy Alcohols Mediated by Trialkyl Borates: The First <i>endo</i>-Mode Epoxide-Opening Reaction through an Intramolecular Metal Chelate
[reaction: see text] Highly efficient C2 selective substitution reactions of 2,3-epoxy alcohols with nucleophiles were developed by using NaN(3)-(CH(3)O)(3)B, NaSPh-(CH(3)O)(3)B, or NaCN-(C(2)H(5)O)(3)B system. The reaction proceeds through novel endo-mode epoxide opening of an intramolecular boron chelate, which was suggested from both experimental and quantum mechanic studies.
Titanium isopropoxide-mediated nucleophilic openings of 2,3-epoxy alcohols. A mild procedure for regioselective ring-opening
作者:Maurice Caron、K. B. Sharpless
DOI:10.1021/jo00209a047
日期:1985.5
Regiochemical control of the ring opening of 1,2-epoxides by means of chelating processes. 5. Synthesis and reactions of some 2,3-epoxy-1-alkanol derivatives
作者:Marco Chini、Paolo Crotti、Lee A. Flippin、Cristina Gardelli、Elena Giovani、Franco Macchia、Mauro Pineschi
DOI:10.1021/jo00057a040
日期:1993.2
In order to study the effect of a remote polar functionality on the regiochemistry of the ring opening of aliphatic epoxides, the synthesis and some nucleophilic additions (methanolysis, azidolysis, and aminolysis) of suitable 2,3-epoxy-1-alkanol derivatives (epoxides trans-1a-d and cis-2) were carried out. The C-3 selectivity commonly observed when nonchelating ring opening conditions are used is lower than when the epoxides are allowed to react in the presence of metal ions (Li+, Mg2+, Zn2+) due to the probable intervention of bidentate-chelated intermediates in the latter case, and in some instances an almost complete C-3 regioselection is obtained. Under identical conditions involving chelation control, trans epoxide la shows higher C-3 selectivity than cis isomer 2. A free hydroxyl functionality is not necessary in order to observe chelation-controlled regioselectivity in the epoxides that we examined.
Regioselective azide opening of 2,3-epoxy alcohols by [Ti(O-i-Pr)2(N3)2]: synthesis of .alpha.-amino acids
作者:Maurice Caron、Paul R. Carlier、K. Barry Sharpless
DOI:10.1021/jo00256a063
日期:1988.10
Design and synthesis of new secretory phospholipase A2 inhibitor of a phospholipid analog
analogs were synthesized by regio and stereoselective epoxide ring opening accompanied by introduction of an amino group. The (4R,5S)-derivative showed stronger inhibitory activity toward type II phospholipaseA2 than the 4-substituted oxazolidinone phospholipid analog previously reported.