Sequenced Reactions with Samarium(II) Iodide. Sequential Intermolecular Carbonyl Addition/Intramolecular Nucleophilic Acyl Substitution for the Preparation of Seven-, Eight-, and Nine-Membered Carbocycles
摘要:
Samarium(II) iodide has been employed to promote a tandem intermolecular carbonyl addition/intramolecular nucleophilic acyl substitution sequence, generating seven- through nine-membered monocyclic, bicyclic, and tricyclic ring systems with good yields and high diastereoselectivities. This tandem reaction consists of an intermolecular reaction followed by an intramolecular ring expansion that results in a formal [m + n] cycloaddition, starting from extremely simple, readily available substrates. The regioselectivity and stereoselectivity of the process arise from a tuning of the reducing power of samarium(II) iodide with nickel(II) iodide in the first step and irradiation with visible light in the second. By using this method, a variety of structural motifs have been assembled rapidly in good yields.
Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
作者:Keri A. Steiniger、Tristan H. Lambert
DOI:10.1021/acs.orglett.1c03029
日期:2021.10.15
efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primaryalcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale
Sodium perborate: A mild and convenient reagent for efficiently oxidizing trialkylboranes
作者:George W Kabalka、Timothy M Shoup、Naganna M Goudgaon
DOI:10.1016/s0040-4039(00)99497-8
日期:1989.1
Sodium perborate, a readily available and inexpensive reagent, efficientlyoxidizes organoboranes. The reagent permits the oxidation of a wide variety of functionally substituted organoboranes. In nearly every instance, the product yields exceed those obtained using standard oxidation procedures.
Complete Diastereocontrol in Intramolecular 1,3-Dipolar Cycloadditions of 2-Substituted 5-Hexenyl and 5-Heptenyl Nitrones: Application to the Synthesis of the β-Lactam Antibiotic 1β-Methylthienamycin
作者:Michael E. Jung、Binh T. Vu
DOI:10.1021/jo952254m
日期:1996.1.1
3,6-disubstituted perhydrocyclopenta[c]isoxazoles has been investigated. An alkyl or aryl substituent at C2 completely controls the stereochemistry of the ring juncture and, in the case of the 5-heptenyl systems, also the stereochemistry of the 3-methyl group. Thus one stereocenter controls the formation of the other three to give a product with four contiguous stereocenters. The use of an ethylene
We report herein an efficient method to synthesize 6-membered cyclic monothiocarbonates which are important intermediates for polymonothiocarbonate synthesisvia the cycloaddition of carbonyl sulfide with 1,3-halohydrin using a low-cost base such as triethylamine and potassium carbonate. This protocol features excellent selectivity and efficiency, mild reaction conditions and easy-to-obtain starting