Selective transformations of 2,3-epoxy alcohols and related derivatives. Strategies for nucleophilic attack at carbon-3 or carbon-2

Abstract

General Procedure for the Workup of the Payne Rearrangement-Opening Reaction of a 2,3-Epoxy Alcohol with an Amine. The reaction mixture is brought to room temperature and concentrated. After all of the volatile amine and most of the water are removed, a semisolid mass remains in the flask. This material is dried under high vacuum and then peracetylated in the usual way. The product thus obtained is taken up in CH2C12 and a minimum amount of water. The aqueous phase is extracted with CH2C12, and the combined organic portions are washed with water (IX), dried (Na2S04), concentrated, and dried under high vacuum to constant weight.Payne Rearrangement-Opening Reaction of (2R*,3R*)-2,3-Epoxy-1 -decanol (4) with Me2NH/KOH. The epoxy alcohol 4 (0.0531 g, 0.309 mmol) in 8 mL of a solution prepared by dissolving KOH (0.6 g, 10.7 mmol) in 20 mL of 40% aqueous Me2NH was stirred at room temperature for 37 h and worked up according to the general procedure to afford 0.0875 g (94%) of a 10:2.8:1.0 mixture of (2R*,3S*)-l-(dimethylamino)-2,3-decanediol diacetate (41a), (2R*,3fi*)-3-(dimethylamino)-l,2-decanediol diacetate (41b), and (2R*,3S*)-2-(dimethylamino)-l,3-decanediol diacetate (41c) as an oil. Purification by flash chromatography (4:1 hexane-acetone) affords 0.0507 g

Compared Behaviors of trans- and cis-α,β-Epoxy-γ,δ-vinyl-silanes Towards Nucleophiles and Bases: High Regioselective Ring Opening and Deprotonation

“…[7][8][9][10] In the latter case, the regioselectivity of these reactions has been proved highly dependent on the substituents of the oxirane. 11 Therefore, following the purpose of developing the reactivity of compounds 1 in stereoselective synthesis, we studied their nucleophilic opening and compared it interestingly with the behavior of a,b-epoxy-silanes 2 on the one hand, and of vinyloxiranes 3 on the other. Indeed a,bepoxy-g,d-vinyl-silanes 1 could be formally considered as the result of the fusion of the two compounds 2 and 3.…”

Synthesis of the Macrocyclic Spermidine Alkaloid (±)-(2R*,3R*)-3-Hydroxycelacinnine

“…We found that the epoxide or bromide functionalities in 7 can be selectively cleaved by the azide ion under specific conditions keeping the other functionality intact. Following the procedure of Behrens and Sharpless for the stereo-and regioselective preparation of b-azido-a-hydroxy-amides [8] [9], we obtained the monoazido derivative 9 in 94% yield by stirring a MeOH solution of 7 with an in situ (MgSO 4 NaN 3 ) preparation of Mg(N 3 ) 2 . In this particular case, the Ph-substituent at the b-position greatly facilitated the epoxide opening, and the reaction proceeded to a full completion after 2 h at room temperature.…”

“…An attempted direct formation of the diazido derivative 10 from 7 required higher temperatures, which led to the formation of by-products. Also, the formation of the C(a) ring-opened isomer was below detectable level, which has to be compared to the 10 : 1 regioselectivity observed in the case of epoxyamides with aliphatic substituents after reflux in methanolic Mg(N 3 ) 2 for several hours, the conditions applied in the original work of Behrens and Sharpless [9]. The facile conversion of azidobromido- amide 9 into diazido derivative 10 was achieved in 96% yield by treating the former with an excess of NaN 3 in DMSO at room temperature for 2 h according to a described general procedure [10].…”

Investigations of the [2,3]-Sigmatropic Rearrangements of Vinylaziridines and Allylic Amines

“…We were pleased to see that the di-and trisubstituted olefins 35b-j showed similar reactivity as the allyl derivative 35a. In general, Eolefins are converted into the corresponding syn products with good diastereoselectivities (entries 1-3), while Zolefins give anti products with moderate to good selectivities (entries [5][6][7][8]. It should be noted that this stereochemical trend is opposite to that normally obtained in the rearrangement of ammonium ylides.…”