55170-74-6Relevant academic research and scientific papers
Asymmetric Evans syn-Aldol Reactions of Terpene-Derived Enals: Scope and Limitations
Kriening, Sebastian,Evagelou, Athanasios,Claasen, Birgit,Baro, Angelika,Laschat, Sabine
, p. 6720 - 6733 (2014)
The (E)- and (Z)-terpene-based aldehydes 6b and 6c with a silyl ether function in the γ-position were prepared and investigated in boron-mediated asymmetric Evans aldol reactions. Screening experiments of chiral N-acylated oxazolidinones 7, which are conveniently accessible from 5-methyl-5-hexenoic acid and Evans oxazolidinone auxiliaries, with various boron triflates and terpenoid neral (Z)-6a as aldehyde component, provided conditions in which highly selective formation of syn-aldol adduct 5a occurred and competing C=C double bond isomerization to 10 was completely suppressed. Applying the optimized conditions to O-silylated aldehydes 6b and 6c and N-acyloxazolidinone derivative (R)-7a confirmed the syn-selectivity and gave the appropriate products syn-5b,c and syn-21b,c in good yields. In the case of neral-derived syn adduct 5a, the configuration of the new stereogenic centers C-2/C-3 could be assigned as (2R,3S). The asymmetric Evans aldol reaction could be successfully applied to terpene-based (E)- and (Z)-aldehydes and N-acyloxazolidinones, giving syn-aldol adducts with high selectivity. Isomerization at the double bond was not observed.
Asymmetric total synthesis of pleurospiroketals A and B
Kobayashi, Toyoharu,Tanaka, Konomi,Ishida, Masako,Yamakita, Natsumi,Abe, Hideki,Ito, Hisanaka
, p. 10316 - 10319 (2018)
The first asymmetric total synthesis of pleurospiroketals A and B has been accomplished in 16 steps from 5-methyl-5-hexenoic acid. Key features of the synthesis are the highly syn-selective Evans aldol reaction, ring-closing metathesis, highly diastereoselective dihydroxylation and acid-mediated spiroketalization.
Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
supporting information, p. 10005 - 10013 (2021/07/19)
The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
CANNABINOID DERIVATIVES AND PRECURSORS, AND ASYMMETRIC SYNTHESIS FOR SAME
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Page/Page column 59, (2021/03/19)
The present disclosure relates to new cannabinoid derivatives and precursors and catalytic asymmetric processes for their preparation. The disclosure also relates to pharmaceutical compositions and pharmaceutical and analytical uses of the new cannabinoid derivatives. For instance, the disclosure relates to the preparation of new precursors, and the use of such precursor compounds for the preparation of isotope labelled cannabinoid products using chiral and achiral catalysts and catalytic processes. The deuterium, carbon-13 and carbon-14 containing compounds can be prepared and purified prior to transformation to the desired individual deuterated cannabinoid products.
SYNTHESIS OF CANNABINOIDS
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Paragraph 0173, (2019/02/05)
Provided are synthesis processes and intermediates for preparing cannabinoids and analogs.
Enantioselective Total Synthesis of Cannabinoids - A Route for Analogue Development
Shultz, Zachary P.,Lawrence, Grant A.,Jacobson, Jeffrey M.,Cruz, Emmanuel J.,Leahy, James W.
, p. 381 - 384 (2018/01/27)
A practical synthetic approach to Δ9-tetrahydrocannabinol (1) and cannabidiol (2) that provides scalable access to these natural products and should enable the generation of novel synthetic analogues is reported.
Enantioselective bromolactonization using an S-alkyl thiocarbamate catalyst
Jiang, Xiaojian,Tan, Chong Kiat,Zhou, Ling,Yeung, Ying-Yeung
supporting information; experimental part, p. 7771 - 7775 (2012/09/07)
The apple never falls far from the tree: S-alkyl thiocarbamate 1 (see scheme, NBP=N-bromophthalimide) was prepared in high yield through a synthetic sequence involving a Newman-Kwart rearrangement of the corresponding O-alkyl thiocarbamates. Compound 1 was used to catalyze bromolactonization, thus providing enantioenriched δ-lactones in excellent yield and enantioselectivity. Copyright
Cu(II)-Catalyzed Olefin Migration and Prins Cyclization: Highly Diastereoselective Synthesis of Substituted Tetrahydropyrans
Ghosh, Arun K.,Nicponski, Daniel R.
, p. 4328 - 4331 (2011/10/05)
Metal-ligand complexes of Cu(OTf)2 with an appropriate bisphosphine ligand have been shown to effectively catalyze the formation of substituted tetrahydropyrans via a sequential olefin migration and Prins-type cyclization. This methodology provides convenient access to a variety of functionalized tetrahydropyrans in excellent diastereoselectivities and good to excellent yields.
Bronsted base-modulated Regioselective Pd-catalyzed intramolecular aerobic oxidative amination of alkenes: Formation of seven-membered amides and evidence for allylic C-H activation
Wu, Liang,Qiu, Shuifa,Liu, Guosheng
supporting information; scheme or table, p. 2707 - 2710 (2009/10/10)
A novel palladium-catalyzed intramolecular aerobic oxidative allylic C-H amination of olefins has been developed. Bronsted base can modulate the regioselectivity, favoring the formation of 7-membered rings. Mechanistic studies using deuterium-labeled substrates as probes support a rate-determining allylic C-H activation/irreversible reductive elimination pathway.
Enantioselective synthesis of Indolizidines bearing quaternary substituted stereocenters via rhodium-catalyzed [2 + 2 + 2] cycloaddition of alkenyl Isocyanates and terminal alkynes
Lee, Ernest E.,Rovis, Tomislav
supporting information; body text, p. 1231 - 1234 (2009/04/07)
An enantioselective synthesis of Indolizidines bearing quaternary substituted stereocenters by way of a rhodium-catalyzed [2 + 2 + 2] cycloaddition of substituted alkenyl Isocyanates and terminal alkynes Is described. The reaction provides lactam products using aliphatic alkynes, whereas aryl alkynes give rise to vlnylogous amide products. Through modification of the phosphoramldlte llgand, high levels of enantloselectlvlty, regloselectlvlty, and product selectivity are obtained for both products.
