Synthesis of gem-Bistriflates: Reaction of Aliphatic Aldehydes with Trifluoromethanesulfonic Acid Anhydride
Reaction of aldehydes 1 with trifluoromethanesulfonic anhydride (2) in the presence of a base 3 or 4 at 0 deg C leads to gem-bistriflates 6 in good yields.
Martinez, Antonio Garcia,Alvarez, Roberto Martinez,Fraile, Amelia Garcia,Subramanian, L. R.,Hanack, M.
Indium tribromide-catalyzed chemoselective dithioacetalization of aldehydes in non-aqueous and aqueous media
Indium tribromide efficiently catalyzes the chemoselective dithioacetalization of aldehydes in the presence of ketones in dichloromethane. The catalyst is also active in water, which can be reused, in the same pot, for several times without any decrease in the yield of reaction. (C) 2000 Published by Elsevier Science Ltd.
Ceschi,De Araujo Felix,Peppe
p. 9695 - 9699
(2007/10/03)
Ceric Ammonium Nitrate as a Convenient Catalyst for Chemoselective Thioacetalisation
A new, mild and chemoselective protection of aldehydes as 1,3-dithiolanes using ceric ammonium nitrate as a catalyst is described.High yields are obtained at room temperature even in the presence of ketones.While alicyclic ketones may also be protected at
Mandal, Pijus Kumar,Roy, Subhas Chandra
p. 7823 - 7828
(2007/10/02)
Chemoselective Protection of Aldehydes as Dithioacetals in Lithium Perchlorate-Diethyl Ether Medium. Evidence for the Formation of Oxocarbenium Ion Intermediate from Acetals
Aldehydes and acetals were very efficiently converted to acyclic and cyclic dithioacetals in 5 M lithium perchlorate/diethyl ether (LPDE) medium at ambient temperature in high yields.Spectroscopic and other experimental evidences strongly suggest the formation of oxocarbenium ion intermediates from acetals in 5 M LPDE which subsequently reacted with thiols to give the dithioacetals.Under the same conditions ketones and their acetals also reacted, albeit very slowly compared to aldehydes and acetals, to yield dithioacetals.The difference in their reactivity was successfully employed in the chemoselective dithioacetalization of aldehydes and acetals in the presence of ketones and their acetals.The chemoselective dithioacetalization of keto aldehydes has been realized with the keto group remaining intact.The present method offers a convenient, efficient, and neutral medium for the deprotection of acetals to aldehydes and also the chemoselective protection of aldehydes to dithioacetals.
Saraswathy, V. Geetha,Sankararaman, S.
p. 4665 - 4670
(2007/10/02)
Comparative radioprotective activity of various pentagonal compounds with two heteroatomes
Various heterocyclic compounds with two heteroatomes were synthesized and their potential radioprotective activity was tested. This study shows the interest of phenylthiazolidines derivatives in chemical radioprotection.
Robbe,Fernandez,Dubief,et al.
p. 235 - 243
(2007/10/02)
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