5655-58-3Relevant articles and documents
Ab initio calculation of optical rotatory dispersion (ORD) curves: A simple and reliable approach to the assignment of the molecular absolute configuration
Giorgio, Egidio,Viglione, Rosario G.,Zanasi, Riccardo,Rosini, Carlo
, p. 12968 - 12976 (2004)
In this paper, both Hartree-Fock (HF) and density functional theory (DFT) methods have been used to make ab initio calculations of the optical rotatory power of selected molecules at several wavelengths; that is, part of the optical rotatory dispersion (ORD) curve has been predicted. This approach constitutes a new, simple, and reliable method to assign the molecular absolute configuration, at least for rigid molecules such as those studied in the present work. In fact, in this way, it is possible to overcome the difficulties connected to some relevant cases, in particular that of (-)-β-pinene, for which even a very high-level (DFT/ B3LYP/6-311++G(2d,2p)) calculation affords the wrong sign of the optical rotation at 633 nm. On the contrary, the predicted ORD curve, even using small basis sets, reproduces (below 400 nm) the experimental trend well, allowing for the correct configurational assignment. This result clearly shows that to have a reliable configurational assignment the comparison between experimental and predicted rotation values must be carried out at different wavelengths and not at a single frequency. The reason for this is that working at wavelengths approaching the absorption maximum the [α]λ values become larger and their prediction becomes more reliable. Coupling the use of an inexpensive instrument (a polarimeter working at a few wavelengths) with the use of a DFT-calculation package can also allow the experimental organic chemist to arrive, quickly and reliably, at the assignment of the molecular absolute configuration.
An Enantiospecific Synthesis of 4-Methylcamphor
Money, Thomas,Palme, Monica H.
, p. 2363 - 2370 (1993)
Treatment of (-)2-methylenebornane (7), derived from (+)-camphor (1), with 45percent HBr/HOAc results in Wagner-Meerwein rearrangement and formation of 4-methylisobornyl bromide (17) in 80-90percent yield.The enantiopurity of (17) was determined by conversion to (+)-4-methylisoborneol (5) and (-)-4-methylcamphor (3).
Aminoxyl-Catalyzed Electrochemical Diazidation of Alkenes Mediated by a Metastable Charge-Transfer Complex
Siu, Juno C.,Parry, Joseph B.,Lin, Song
supporting information, p. 2825 - 2831 (2019/02/14)
We report the development of a new aminoxyl radical catalyst, CHAMPO, for the electrochemical diazidation of alkenes. Mediated by an anodically generated charge-transfer complex in the form of CHAMPO-N3, radical diazidation was achieved across a broad scope of alkenes without the need for a transition metal catalyst or a chemical oxidant. Mechanistic data support a dual catalytic role for the aminoxyl serving as both a single-electron oxidant and a radical group transfer agent.
Incubation of 2-methylisoborneol synthase with the intermediate analog 2-methylneryl diphosphate
Chou, Wayne K.W.,Gould, Colin A.,Cane, David E.
, p. 625 - 631 (2017/05/29)
Incubation of synthetic 2-methylneryl diphosphate (2-MeNPP, 10) with 2-methylisoborneol synthase (MIBS) gave a mixture of products that differed significantly from that derived from the natural substrate (E)-2-methylgeranyl diphosphate (3, 2-MeGPP). The proportion of (-)-2-methylisoborneol (1) decreased from 89 to 17% while that of 2-methylenebornane (4) increased from 10 to 26%, with the relative yields of the isomeric homo-monoterpenes 2-methyl-2-bornene (5) and 1-methylcamphene (6) remaining essentially unchanged (a k cat 0.105±0.007 s -1, K m 95±49 μm and k cat /K m 1.11 × 10 3 M -1 s -1. Taken together with earlier X-ray crystallographic studies of MIBS, as well as previous investigations of the mechanistically related plant monoterpene cyclase, bornyl diphosphate synthase, these results provide important insights into the binding and cyclization of both native substrates and intermediates and their analogs.
Stereoselective synthesis of constrained norbornane-derived spiro-β-lactams
Cremonesi, Giuseppe,Dalla Croce, Piero,Forni, Alessandra,La Rosa, Concetta
, p. 1175 - 1182 (2013/03/13)
New enantiopure polycyclic norbornane-derived spiro-β-lactams were synthesized by means of a Staudinger ketene-imine reaction between unsymmetrical bicyclic chiral ketenes, generated from differently substituted norbornane carboxylic acids, and (E)-N-benzyl-N-(phenylmethylene)amine, with high yields and moderate to good stereoselectivities. The diastereoisomeric results were rationalized taking into account the increasing steric encumbrance present on the norbornane skeleton and the stability of the products. The configurations of the newly formed stereocenters of spiro-β-lactams were assigned on the basis of 2D NMR experiments and X-ray analysis. Spiro-β-lactams were subjected to acid hydrolysis obtaining the corresponding norbornane-derived β-amino acids.
Cloning and characterization of Pfl-1841, a 2-methylenebornane synthase in Pseudomonas fluorescens PfO-1
Chou, Wayne K.W.,Ikeda, Haruo,Cane, David E.
supporting information; experimental part, p. 6627 - 6632 (2011/10/04)
The pfl-1841 gene from Pseudomonas fluorescens PfO-1 is the only gene in any of the three sequenced genomes of the Gram-negative bacterium P. fluorescens, that is, annotated as a putative terpene synthase. The predicted Pfl-1841 protein, which harbors the two strictly conserved divalent metal binding domains found in all terpene cyclases, is closely related to several known or presumed 2-methylisoborneol synthases, with the closest match being to the MOL protein of Micromonaspora olivasterospora KY11048 that has been implicated as a 2-methylenebornane synthase. A synthetic gene encoding P. fluorescens Pfl-1841 and optimized for expression in Escherichia coli was expressed and purified as an N-terminal His6-tagged protein. Incubation of recombinant Pfl-1841 with 2-methylgeranyl diphosphate produced 2-methylenebornane as the major product accompanied by 1-methylcamphene as well as other minor, monomethyl-homomonoterpene hydrocarbons and alcohols. The steady-state kinetic parameters for the Pfl-1841-catalyzed reaction were K M=110±13 nM and kcat=2.4±0.1×10 -2 s-1. Attempts to identify the P. fluorescens SAM-dependent 2-methylgeranyl diphosphate synthase have so far been unsuccessful.
Convenient method for epoxidation of alkenes using aqueous hydrogen peroxide
Man, Kin Tse,Klawonn, Markus,Bhor, Santosh,Doebler, Christian,Anilkumar, Gopinathan,Hugl, Herbert,Maegerlein, Wolfgang,Beller, Matthias
, p. 987 - 990 (2007/10/03)
(Chemical Equation Presented) The complex [Ru(tpy)(pydic)] (1a) is an active catalyst for epoxidation of alkenes by aqueous 30% hydrogen peroxide in tertiary alcohols. The protocol is simple to operate and gives the corresponding epoxides in good to excellent yields. Chiral enantiopure [Ru(tpy*)(pydic) ] complexes have been synthesized and successfully applied in this procedure.
A simple synthethic route to 4-methylcamphor: mechanistic aspects
Clase, J. Andrew,Li, Diana L. F.,Lo, Linda,Money, Thomas
, p. 1829 - 1836 (2007/10/02)
A mechanism proposed for the rearrangement of (+)-2-methylbornane (8) to a mixture of (+)-4-methylisobornyl acetate (5) and its enantiomer (ent-5) is supported by evidence obtained by investigating the rearrangement of deuterated 2-methylenebornane.
Alkylmetal Asymmetric Reduction. 18. Starting Materials in the Preparation of New Chiral Reducing Agents: Synthetic Approach to Primary Alkyl Halides Derived from (+)-Camphor
Falorni, Massimo,Lardicci, Luciano,Giacomelli, Giampaolo
, p. 5291 - 5294 (2007/10/02)
2,2-Dimethyl-3-(chloromethyl)bicycloheptane (camphanyl chloride), camphanyl bromide, 1,7,7-trimethyl-2-(chloromethyl)bicycloheptane , and 2-(bromomethyl)bornane were prepared from (+)-camphor.All these compounds were obtained as mixture of exo and endo isomers in various ratios depending upon the synthetic path adopted.A loss of diastereomeric purity during the halogenations of corresponding alcohols was observed.
