Intramolecular Bicyclizations of Tosylamide-Containing Alkynyliodonium Salts as an Efficient Entry into Polycyclic Alkaloid Skeleta

1-(Organosulfonyloxy)-3(1H)-1,2-benziodoxoles: Preparation and Reactions with Alkynyltrimethylsilanes

“…It is known from the literature that the noncyclic aryliodosyl sulfonates, such as Koser's reagent PhI(OH)OTs and Zefirov's reagent PhI(OTf)O(OTf)IPh, are highly reactive toward unsaturated organic substrates and other carbon nucleophiles . The noncyclic aryliodosyl sulfonates are especially useful reagents for the preparation of alkynyliodonium salts by the reaction with silylated or stannylated alkynes. , Assuming that the cyclic aryliodosyl sulfonates 3 , 5 have a similar reactivity pattern, we investigated reactions of sulfonates 3 and 5 with silylacetylenes. Mesylates ( 3b , 5b ) and tosylates ( 3c , 5c ) were found to have low reactivity in these reactions.…”

From Solvolysis to Self-Assembly

“…This provides a nice alternative to the Nazarov155 and Pauson-Khand156,157 reactions for the synthesis of cyclopentenones. Feldman and co-workers have also used this tandem Michael-addition/carbene-insertion procedure to prepare highly substituted dihydropyrrole derivatives158 as well as polycyclic alkaloids 159. This method has also been used to prepare thiazoles160 a well as benzofurans,161 furopyridines162 and 2-mercaptothiazoles 163…”

Chapter 6. Heterocyclic compounds

“…Reaction of 2-fury1 phenyl thioketone (59) with diazobis(phenylsulfony1)methane gives the furo[2,3-c]thiophene (60) in 62% yield (Scheme 25).j7 Phenyliodonium bis(phenylsulfony1)methane brings about the same reaction and a thiophene, a pyrrole or their benzo-derivatives can take the place of the furan moiety. An alternative synthesis of furo[2,3-c]pyrroles is described3* and their Diels-Alder reactions are investigated.…”

“…Cleavage of the chiral auxiliary leaves pyrrolidinecarboxylic acid ( 99 Tributyltinalkynes such as (105) are precursors of alkynyliodonium salts (106), which are themselves isolable, but are best treated immediately with strong base to deliver a cyclized amine such as (107) (Scheme 43). 59 Photochemical irradiation of trimethylsilylmethylphthalimide ( 108) gives an azomethine ylide which undergoes typical reactions giving, for example, (109) (Scheme 44). An azomethine ylide can also be generated photochemically from ( 1Peter W. SheIdrake Acyl azide (113) was heated in the expectation of obtaining an isocyanate.62 However, 1,1,7-trimethylindazol-3-ium-5-olate (1 14) is found to be the product; its structure is confirmed by X-ray crystallography (Scheme 46).…”