Intramolecular addition heteronucleophiles

The gold-catalyzed inter- and intramolecular addition of carbon- and heteronucleophiles to alkynes leads to a wide variety of products [6]. In the case of nitrogen nucleophiles, the addition of amines, anihnes [67, 68], imines [69], pyridines and azides [72] is possible (Scheme 1.1). 

Another common trapping method is an intramolecular aldol reaction of the initially formed anion, as shown in equation (91) and Schemes 53 and 54.% In the first case, an aldol-like trapping of the iminium salt produced (411 equation 91 ).96b The initial heteronucleophile in the other two cases is ultimately lost from the product by oxidation and elimination, so that the overall process is C—C bond formation at the a-center of an enone. Thus, treatment of the formyl enone (412 Scheme 53) with an aluminum thiolate afforded in 60% yield the trapped product (413) which could be oxidized and eliminated to give (414).96c Addition of the corresponding aluminate species to the ketoacrylate (415 Scheme 54) produced only one diastereomer of the aldol product (416) which was converted into the alkene (417) in excellent yield.96 1... 

Pyrimidine reacts with trimethylsilyl cyanide and benzoyl chloride with aluminum chloride as catalyst, to give the Reissert-type compound (366) <81JHC443>. The intermediate acylpyrimidinium cation (367) adds a soft nucleophile such as the silyl ether of acetophenone, and the adduct rapidly undergoes a second A-quaternization to (368) with a subsequent nucleophilic attack to form (369) (Scheme 61). The reactive intermediate can also be trapped by reactions with heteronucleophiles <88JCS(P1)725>. Intramolecular nucleophilic addition is shown in the formation of the spiran derivative (370) <92JOC2526>. 

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