Regioselective Iodoazidation of Alkynes: Synthesis of α,α-Diazidoketones
摘要:
Aryl alkyl alkynes reacted with N-iodosuccinimide (NIS) and trimethylsilyl azide (TMSN3), leading to α,α-diazidoketones via the regioselective addition of IN3 to alkynes. Huisgen cyclization of α,α-diazidoketones generated bis-triazole compounds.
The palladium-catalyzed reaction of propargylic carbonates with Meldrum's acidderivatives proceeds smoothly in the presence of Pd(OAc)2 and P(2-furyl)3 in THF at 80 °C to give substitution products. The substitution products can be useful intermediates for the stereoselective synthesis of functionalized (Z)-γ-alkylidene-γ-butyrolactones.
Titanium/Palladium-Mediated Regioselective Propargylation of Ketones using Propargylic Carbonates as Pronucleophiles
作者:Alba Millán、Luis Álvarez de Cienfuegos、Ana Martín-Lasanta、Araceli G. Campaña、Juan M. Cuerva
DOI:10.1002/adsc.201000655
日期:2011.1.10
for the synthesis of homopropargylic alcohols usingpropargyliccarbonates as pronucleophiles is reported. The reaction is based on a combination of transition metal (palladium) and radical chemistry (titanium). The reaction takes place with an excellent regioselectivity and tolerates a great degree of substitution of the starting propargyliccarbonate, thus being an interesting tool in the context
Ketones 1 were converted to of-quaternary of-vinyl ketones 2 by a two-step formal allylic carbon insertion between ketone carbonyl and alpha carbons, which involves the reaction of 1 with propargyltitanium reagents, derived from propargyl carbonates 3 and a divalent titanium reagent Ti(O-i-Pr)(4)/2i-PrMgCl, and the following rearrangement of the resulting alpha-allenyl alcohols 4 with NBS. (c) 2008 Elsevier Ltd. All rights reserved.