- One-Pot Substitution of Aliphatic Alcohols Mediated by Sulfuryl Fluoride
-
The Mitsunobu reaction is a powerful transformation for the one-pot activation and substitution of aliphatic alcohols. Significant efforts have focused on modifying the classic conditions to overcome problems associated with purification from phosphine-based byproducts. Herein, we report a phosphine free method for alcohol activation and substitution that is mediated by sulfuryl fluoride. This new method is effective for a wide range of primary alcohols using phthalimide, di-tert-butyl-iminodicarboxylate, and aromatic thiol nucleophiles in 74 % average yield. Activated carbon nucleophiles and a deactivated phenol were also effective for this reaction in good yields. Secondary alcohols were also successful substrates using aryl thiols, affording the corresponding sulfides in 56 % average yield with enantiomeric ratios up to 99:1. This new protocol has a distinct synthetic advantage over many existing phosphine-based methods as the byproducts are readily separable. This feature was exploited in several examples that did not require chromatography for purification. Furthermore, the mild reaction conditions enabled further in situ derivatization for the one-pot conversion of alcohols to amines or sulfones. This method also provides a boarder nucleophile scope compared to existing phosphine-free methods.
- Dubois, Rudy,Epifanov, Maxim,Hodgson, Jack W.,Mo, Jia Yi,Sammis, Glenn M.
-
supporting information
p. 4958 - 4962
(2020/04/22)
-
- A novel series of 2,5-substituted tryptamine derivatives as vascular 5HT(1B/1D) receptor antagonists
-
The design, synthesis, and activity of a novel series of 2,5- substituted tryptamine derivatives at vascular 5HT(1B)-like receptors is described. Several important auxiliary binding sites of the 5HT(1B)-like receptor have been proposed following various modifications to the 2- substituent and especially to the methylene- or ethylene-linked 5-side chain. Careful design of new molecules based on a proposed pharmacophoric model of the 5HT(1B)-like receptor has resulted in the discovery of ethyl 3-[2- (dimethylamino)ethyl]-5-[2-(2,5-dioxo-1-imidazolidinyl)ethyl]-1H-indole-2- carboxylate (40), a highly potent, silent, competitive, and selective antagonist which shows affinity at the vascular 5HT(1B)-like receptors only. Changes to the size of the 2-ester substituent have a significant effect on affinity at the 5HT(1B)-like receptor and other receptors. Prudent placement of the carbonyl substituent in the heterocycle of the 5-side chain is crucial for good affinity and selectivity over the 5HT(2A) and other receptors. Several key structural and electronic features were identified which are crucial for producing antagonism within a tryptamine-based series. An electron deficient indole ring system appears essential in order to achieve antagonism, and this is achieved by the inclusion of electron-withdrawing groups at the 2-position of the indole ring. The molecule displacement within the receptor resulting from the inclusion of the bulky 2-substituents also enhances antagonism as this results in the removal of the Π electon density of the indole ring from the region of the receptor normally occupied by the indole ring of 5HT. There also appears to be a structural requirement on the side chain incorporating the protonatable nitrogen, and this is achieved by the inclusion of the bulky 2-ester group which neighbors the 3-ethylamine side chain.
- Moloney, Gerard P.,Robertson, Alan D.,Martin, Graeme R.,MacLennan, Steven,Mathews, Neil,Dodsworth, Susan,Sang, Pang Yih,Knight, Cameron,Glen, Robert
-
p. 2347 - 2362
(2007/10/03)
-