Cobalt-Catalyzed Diastereoselective [4+2] Annulation of Phosphinamides with Heterobicyclic Alkenes at Room Temperature

Cobalt-catalyzed sp(2) C-H bond functionalization of diarylphosphinamides with heterobicyclic alkenes was demonstrated at room temperature employing commercially available cobalt(II)-salts. The effectiveness of this strategy was illustrated with the reaction of various 8-aminoquinoline derived phosphinic amides and 7-oxa/azabenzonorbornadienes. The reaction conditions exhibited excellent functional group tolerance and high diastereoselectivities. Furthermore, extension of this approach to the preparation of polyaryl cyclic phosphinamides was achieved through the dehydrative ring opening/aromatization sequence

Cobalt-catalyzed aryl C-H activation and highly regioselective intermolecular annulation of sulfonamides with allenes

Herein we describe a cobalt-catalyzed C-H activation of aryl and heteroaryl sulfonamides and their intermolecular heteroannulation reaction with allenes, providing a convergent strategy for the synthesis of biologically interesting heterocyclic scaffolds. Carbometallation of allenes proceeds selectively through a Co-alkenyl pathway for a wide range of electron-poor and electron-rich allenes

Cobalt-Catalyzed sp(2)-C-H Activation: Intermolecular Heterocyclization with Allenes at Room Temperature

The reactivity of allenes in transition-metal-catalyzed C-H activation chemistry is governed by the formation of either alkenyl-metal (M-alkenyl) or metal-pi-allyl intermediates. Although either protonation or a beta-hydride elimination is feasible with a M-alkenyl intermediate, cyclization has remained unexplored to date. Furthermore, due to the increased steric hindrance, the regioselectivity for the intramolecular cyclization of the metal-pi-allyl intermediate was hampered towards the more substituted side. To address these issues, a unified approach to synthesize a diverse array of biologically and pharmaceutically relevant heterocyclic moieties by cobalt-catalyzed directed C-H functionalization was envisioned. Upon successful implementation, the present strategy led to the regioselective formation of dihydroisoquinolin- 1(2H)-ones, isoquinolin-1(2H)-ones, dihydropyridones, and pyridones

The stereoselective total synthesis of aculeatin A and B via Prins cyclization

The total synthesis of aculeatins A and B is described proving the versatility of Prins cyclization in natural product synthesis. The approach is convergent and highly stereoselective. Morpholine amide coupling with an alkyne and PIFA-mediated oxidative spirocyclization were utilized as key steps

Stereoselective synthesis of (−)-PF1163A via Prins cyclization

A highly stereoselective and convergent total synthesis of PF1163 A is described while proving the versatility of Prins cyclization in natural product synthesis. The Prins cyclization, Yamaguchi esterification, and ring-closing metathesis reactions are the key steps utilized in the synthesis of macrolactone

The first stereo selective total synthesis of (3R),(5R)-5-hydroxy-de-O-methyllasiodiplodin and its epimer via an RCM protocol

The first total synthesis of (3R),(5R)-5-hydroxy-de-O-methyllasiodiplodin and its epimer is reported from malic acid. The adopted approach is highly convergent and stereoselective. The strategy utilizes syn selective reduction and ring-closing metathesis as key steps

The first example of alkynylation of propargylic alcohols with alkynylsilanes catalyzed by molecular iodine

Aryl propargyl alcohols undergo smooth alkynylation with alkynylsilanes in the presence of 10 mol % of iodine under mild and neutral conditions to produce 1,4-diynes in excellent yields with high selectivity. The use of readily available molecular iodine makes this method simple, convenient, cost-effective and practical

The stereoselective total synthesis of xestodecalactone C and epi-sporostatin via the Prins cyclisation

Syntheses of xestodecalactone C and epi-sporostatin are described utilising Prins cyclisations, Mitsunobu reaction and intramolecular Friedel-Crafts acylation. The approach is convergent and highly stereoselective

First stereoeselective total synthesis of sporostatin and determination of absolute configuration

The first simple and efficient total synthesis of sporostatin has been accomplished in five steps starting from (S)-propylene oxide. The synthesis utilizes simple reactions such as esterification, cross-metathesis, and intramolecular Friedel-Crafts reaction as key steps

The silylalkyne-Prins cyclization: a novel synthesis of 4-iododihydropyrans

The silylated secondary homopropargylic alcohols undergo smooth coupling with aldehydes in the presence of molecular iodine under mild reaction conditions to produce 4-iododihydropyrans in good yields. This method is highly stereoselective, affording cis-dihydropyrans exclusively