Arenes intramolecular reactions, termination

Domino or cascade reactions provide valuable approaches, especially to various carbo- and heterocyclic systems with three, four, or even more annelated rings. The Heck reaction has successfully been employed in various inter-inter-, intra-inter-, inter-intra-, as well as all-intramolecular reaction cascades, hi this section, the termination of these processes by alkenes, arenes, and related ir-bond systems such as alkynes and allenes will be described. A cascade Heck reaction is considered to consist of an oxidative addition of a heteroatom-carbon bond to palladium (starter), carbopalladation of a nonaromatic carbon-carbon double or triple bond without immediate dehydropalladation (relay), one, two, or more fimher car-bopalladation(s) of a carbon-carbon double or triple bond, and eventually ensuing dehydropalladation. Crucial for a cascade reaction of this kind to occur is the blockage or retardation of a dehydropalladation at one of the intermediate stages by using 1,1-disubsti-tuted alkenes and appropriately substimted cycloalkenes, bicycloalkenes, or alkynes as relays since they give kinetically stable alkyl- or alkenylpalladium intermediates, respectively. 

Denmark pursued intramolecular alkyne hydrosilylation in the context of generating stereodefined vinylsilanes for cross-coupling chemistry (Scheme 21). Cyclic siloxanes from platinum-catalyzed hydrosilylation were used in a coupling reaction, affording good yields with a variety of aryl iodides.84 The three steps are mutually compatible and can be carried out as a one-pot hydro-arylation of propargylic alcohols. The isomeric trans-exo-dig addition was also achieved. Despite the fact that many catalysts for terminal alkyne hydrosilylation react poorly with internal alkynes, the group found that ruthenium(n) chloride arene complexes—which provide complete selectivity for trans-... 

In a series of fascinating studies, Dixneuf s group has demonstrated the capability of arene-ruthenium complexes for promoting the intramolecular cyclization of (Z)-3-methylpent-2-en-4-yn-l-ols, such as 116 and 118, to furan derivatives 117 and 119 (Scheme 32) [53,55-57]. This reaction corresponded to the intramolecular Markovnikov addition of a hydroxyl group to a non-activated terminal triple bond. It was found that the czs-geometry of double bond is crucial for the... 

Intramolecular addition reactions of arenes and aryl olefins with secondary and primary amines have proven to be of broader scope than the analogous reactions with tertiary amines. The intramolecular addition of nonconjugated o-allylanilines 51 to yield the 2-methylindolines 52 was reported by Koch-Pomeranz et al. in 1977. Intramolecular electron transfer from the singlet aniline to the ground state alkene followed by N-H proton transfer to the alkene terminal carbon was proposed to account for the regioselective formation of indolines. Proton transfer to the internal carbon would yield tetrahydroquinolines, which were... 

The oxidative dearomatization of appropriately substituted phenolic substrates resulting in intramolecular cyclization with the formation of spirocyclic products represents one of the most powerful synthetic tools in modern organic synthesis (Seetion 3.1.11). Kita and coworkers were the first to report a catalytic variant of the oxidative spirocyclization reaction based on the in situ regeneration of a [bis(trifluoroacetoxy)iodo]arene from iodoarene using mCPBA as a terminal oxidant [2]. In a representative example, the oxidation of... 

As in the cases of termination by lactonization and lactamization, some specially structured alkenes, such as norbomene and related alkenes, can participate in intermolecular carbopalladation-carbonylative ketonization tandem processes. In the reactions shown in Scheme 22, the acylpalladium intermediates undergo intramolecular acylpalladation with arenes to provide ketones. ... 

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