Chromium—Arene Complexes

The Natural Products Chemistry of the Gorgonian Genus Pseudopterogorgia (Octocorallia: Gorgoniidae)

“…This encouraged Fenical and coworkers to design an efficient semisynthetic pathway to convert the more abundant pseudopterosins A-D (1-4) into pseudopterosin E (5). [39][40][41][42][43][44][45][46][47][48][49][50][51][52] These syntheses provided the first compelling evidence that pseudopterosins G-J (7-10) are diastereomeric at C1 relative to the pseudopterosins A-F (1)(2)(3)(4)(5)(6), not at C7 as originally reported. Since then, several enantiospecific total syntheses of pseudopterosin A (1) and pseudopterosin E (5) have been reported, [33][34][35][36] and syntheses for the aglycon component of these Pss and its methylated derivatives have also been outlined.…”

An Approach to Serrulatane Diterpenes via endo-Selective Conjugate Nucleophilic Addition to Arene-Cr(CO)3 Complexes

“…We here report a short, efficient, and completely stereoselective entry toward compounds related to 1 by exploiting arene-Cr(CO) 3 chemistry . Moreover, we show that the unusual endo selectivity of conjugate nucleophilic addition 6 to 1-ethylidene-tetralin-Cr(CO) 3 derivatives, used as a key step in this synthesis, is rather general and must result from an unprecedented attracting interaction of the nucleophile with the metal carbonyl unit.…”

Rhodium-Catalyzed Addition of (Trialkylsilyl)arenes to Electrophiles via π-Coordination-Driven C–Si Bond Activation

“…The tendency of a C–Si bond to undergo heterolysis is linked to the stability of the corresponding aryl carbanion, and thus the presence of an electron-withdrawing substituent, such as carbonyl and nitro, facilitates desilylation of (trialkylsilyl)­arenes . In this context, the electrophilic nature of tricarbonylchromium (Cr­(CO) 3 ), widely recognized for its ability to trigger reactions that would not proceed with unbound arenes, , offers an avenue for promoting the heterolytic cleavage of C­(aryl)–Si bonds through η 6 -coordination. Indeed, addition reactions between Cr­(CO) 3 -complexed (trimethylsilyl)­arenes and electrophiles (e.g., ketones, benzoyl fluoride) in the presence of fluoride, KH, or KO t Bu have been accomplished .…”