A facile synthesis of bicyclo[m.n.1]alkan-1-ols. Evidence for organosamarium intermediates in the samarium(II) iodide promoted intramolecular Barbier-type reaction
摘要:
Samarium(II) iodide (SmI2) has been successfully employed as a reductive coupling agent for the intramolecular Barbier-type synthesis of bicyclo[m.n.1]alkan-1-ols. Thus, a variety of 3-(omega-iodoalkyl)cycloalkanones, upon treatment with SmI2 and a catalytic quantity of iron complex in tetrahydrofuran (THF), provide the title compounds in excellent yields. The reaction is quite general for the construction of diverse bicyclic ring systems, including the highly strained bicyclo[2.1.1]hexan-1-ol. In addition to exploring the synthetic utility of this reaction, studies have been performed which provide insight on the mechanistic details of the SmI2-promoted intramolecular Barbier-type synthesis. Compelling evidence for the intermediacy of organosamarium species has thus been gathered.
Total syntheses of the proposed structures of cuevaene A
摘要:
Two proposed structures of cuevaene A were synthesized and the NMR spectra of both structures are proved to be inconsistent with those of the natural product. The structure of cuevaene A is still unclear and needs to be revised. (C) 2010 Elsevier Ltd. All rights reserved.
The Kharasch reaction revisited: CuX3Li2-catalyzed conjugate addition reactions of Grignard reagents
作者:Manfred T. Reetz、Alois Kindler
DOI:10.1016/0022-328x(95)05699-p
日期:1995.10
The conjugate addition of Grignardreagents RMgX to α,β-unsaturated ketones and esters is effectively catalyzed by soluble copper ate-complexes of the type CuX3Li2, e.g. CuI · 2LiCl. In the presence of Me3SiCl the corresponding ketone enolsilanes are formed in high yield and selectivity. Diasteroselectivity in the case of chiral ketones is similar to that observed by using stoichiometric amounts of
格氏试剂RMgX向α,β-不饱和酮和酯的共轭加成可通过CuX 3 Li 2类型的可溶性铜酸酯络合物(例如CuI·2LiCl )有效地催化。在Me 3 SiCl存在下,可以高产率和高选择性形成相应的酮烯醇硅烷。在手性酮的情况下,非对映选择性类似于通过使用化学计量的铜酸盐R 2 CuLi所观察到的非对映选择性。因此,CuX 3 Li 2催化的格氏试剂的1,4-加成可能是工业上可行的方法。
A Strategy toward Icetexane Natural Products
作者:Daniel J. Moon、Mohammad Al‐Amin、Robert S. Lewis、Kimberly M. Arnold、Glenn P. A. Yap、Jennifer Sims‐Mourtada、William J. Chain
DOI:10.1002/ejoc.201800707
日期:2018.7.6
Icetexane diterpenoids are richly complex polycyclic naturalproducts that have been described with a variety of biological activities. We report here a general synthetic approach toward the 6-7-6 tricyclic core structure of these interesting synthetic targets based on a two-step enolate alkylation and ring-closing metathesis reaction sequence.
New method for preparing βγ-unsaturated ketones: use of phenylselenoacetaldehyde
作者:Derrick L. J. Clive、Charles G. Russell
DOI:10.1039/c39810000434
日期:——
Zinc enolates derived from ketones condense efficiently with phenylselenoacetaldehyde and the products are converted into βγ-unsaturated kmmetones by the action of methanesulphonyl chloride and triethylamine.
Rules for ring-fusion geometry and the preparation of trans- or cis-fused bicyclic compounds by radical closure
作者:Derrick L. J. Clive、David R. Cheshire、Lu Set
DOI:10.1039/c39870000353
日期:——
Aldol condensation with (phenylseleno)acetaldehyde and radical cyclization leads to cis-fusedbicycliccompounds when applied (Scheme 1) to esters of cycloalk-2-enylacetic acid; trans-isomers are formed when the reactions are used (Scheme 2) in conjunction with organocuprate-mediated addition to cycloalkenones.
A practical method for regiocontrolled one-carbon ring contraction
作者:Matthew J. Mitcheltree、Zef A. Konst、Seth B. Herzon
DOI:10.1016/j.tet.2013.04.027
日期:2013.7
A practical and efficient method for the perfluorobutanesulfonyl azide-mediated one-carbon ringcontraction of cyclic enoxysilanes is described. High-yielding procedures for the elaboration of the resulting N-acyl sulfonamide products are reported.