Synthesis of lactones and related compounds
Cu/nitroxyl catalysts promote a highly efficient and selective aerobic oxidative lactonization of diols under mild reaction conditions using ambient air as the oxidant. A Cu/ABNO catalyst system shows excellent reactivity with symmetrical diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system displays excellent chemo- and regioselectivity for the oxidation of less hindered unsymmetrical diols.
X. Xie, S. S. Stahl, J. Am. Chem. Soc., 2015, 137, 3767-3770.
A new copper-catalyzed oxidative [3 + 2] cycloaddition of alkenes with anhydrides using oxygen as the sole oxidant affords γ-lactones in good to excellent yield. This catalyzed cyclization process has a broad substrate scope.
L. Huang, H. Jiang, C. Qi, X. Liu, J. Am. Chem. Soc., 2010, 132, 17652-17654.
Various γ-lactones can be accessed readily by utilizing a Au-catalyzed tandem cycloisomerization/oxidation of homopropargyl alcohols. Notably, the mechanism of this strategy is distinctively different from the related Ru-catalyzed reactions where a ruthenium vinylidene intermediate occurs.
C. Shu, M.-Q. Liu, Y-Z. Sun, L.-W. Ye, Org. Lett., 2012, 14, 4958-4961.
A mild, general, and functional group tolerant intramolecular hydroalkoxylation and hydroacyloxylation of unactivated olefins using a Co(salen) complex, an N-fluoropyridinium salt, and a disiloxane reagent at room temperature provides five- and six-membered cyclic ethers and lactones. The powerful Co catalyst system also enables the deprotective hydroalkoxylation of O-protected alkenyl alcohol and hydroacyloxylation of alkenyl esters.
H. Shigehisa, M. Hayashi, H. Ohkawa, T. Suzuki, H. Okayasu, M. Mukai, A. Yamazaki, R. Kawai, H. Kikuchi, Y. Satoh, A. Fukuyama, K. Hiroya, J. Am. Chem. Soc., 2016, 138, 10084-10087.
AuCl3-catalyzed electrophilic cyclization of 4-bromo-3-yn-1-ols via hydroxyl-assisted regioselective hydration in wet toluene enables the synthesis of γ-butyrolactones in good yields. Various secondary and tertiary alcohols including benzylic systems were found to be equally reactive.
M. S. Reddy, Y. K. Kumar, N. Thirupathi, Org. Lett., 2012, 14, 824-827.
A new and reliable method for the direct construction of biologically important aryl lactones and phthalides from carboxylic and benzoic acids is based on selective benzylic C-H abstraction in the presence of hypervalent iodine(III) reagents and KBr.
T. Dohi, N. Takenaga, A. Goto, A. Maruyama, Y. Kita, Org. Lett., 2007, 9, 3129-3132.
An efficient, chemo- and enantioselective ketone hydroacylation enables the direct preparation of lactones from keto alcohols in the presence of Noyori's asymmetric transfer hydrogenation catalyst. The alcohol is oxidized in situ to an aldehyde, obviating the need to prepare sensitive keto aldehyde substrates.
S. K. Murphy, V. M. Dong, J. Am. Chem. Soc., 2013, 135, 5553-5556.
Tetrabutylammonioum fluoride is a catalyst for the nucleophilic addition of silyl ketene acetals to epoxides providing γ-lactones with high regioselectivities and yields. This metal-free catalytic approach works in a very efficient manner under solvent-free conditions.
S. Bonollo, A. Z. Ahmady, C. Petrucci, A. Marocchi, F. Pizzo, L. Vaccaro, Org. Lett., 2014, 16, 5721-5723.
Silver(I) triflate catalyzes intramolecular additions of hydroxyl or carboxyl groups to olefins in good to excellent yields for a range of substrates under relatively mild conditions. This reaction is one of the simplest methods to construct cyclic ethers or lactones.
C.-G. Yang, N. W. Reich, Z. Shi, C. He, Org. Lett., 2005, 7, 4553-4556.
A highly enantioselective chromium-catalyzed carbonyl 2-(alkoxycarbonyl)allylation followed by lactonization enables the synthesis of enantioenriched α-exo-methylene γ-butyrolactones. Various functional groups are compatible under the mild reaction conditions.
W. Chen, Q. Yang, T. Zhou, Q. Tian, G. Zhang, Org. Lett., 2015, 17, 5236-5239.
The room-temperature nucleophilic addition of vinyl azides to propargylic alcohols in the presence of a catalytic amount of BF3·Et2O provides 4-ynamides. The procedure is operationally convenient, shows broad substrate scope, and tolerates many functional groups. Further, a Vilsmeier intramolecular cyclization of 4-ynamides gives dihydrofuran-2(3H)-ones with the alkyne group as the nucleophile.
J. Zheng, J.-H. Lin, L.-Y. Yu, Y. Wei, X. Zheng, J.-C. Xiao, Org. Lett., 2015, 17, 6126-6129.
A desymmetrization of prochiral diesters with a chiral phosphoric acid catalyst produces highly enantioenriched lactones in excellent yield. Various substitution patterns are tolerated, many of which result in the generation of an enantioenriched all-carbon quaternary center. Manipulation of the lactone products to useful small building blocks is also described.
J. Wilent, K. S. Petersen, J. Org. Chem., 2014, 79, 2303-2307.
The hypervalent iodine reagent PIFA promotes the efficient intramolecular electrophilic cyclization of easily accessible alkynylamides and alkynyl carboxylic acids, leading to pyrrolidinone and lactone skeletons, respectively. A synthetic study and a mechanistic proposal for these transformations are presented.
I. Tellitu, S. Serna, M. T. Herrero, I. Moreno, E. Domínguez, R. SanMartin, J. Org. Chem., 2007, 72, 1526-1529.
A metal-free photoredox system, consisting of an acridinium photocatalyst, an organic base, and molecular sieve (MS) 4 Ĺ, promotes chemoselective photooxidation of aryl alkenes in the presence of oxygen. This oxo-acyloxylation of aryl alkenes provides a green, practical, and metal-free protocol for a wide range of α-acyloxy ketones.
Q.-B. Zhang, Y.-L. Ban, D.-G. Zhou, P.-P. Zhou, L.-Z. Wu, Q. Liu, Org. Lett., 2016, 18, 5256-5259.
Homogeneous carboamination, carboalkoxylation and carbolactonization of terminal alkenes are realized via oxidative gold catalysis, providing expedient access to various substituted N- or O-heterocycles. Deuterium-labeling studies established the nature of the alkene functionalization and the indispensible role of Au(I)/Au(III) catalysis.
G. Zhang, L. Cui, Y. Wang, L. Zhang, J. Am. Chem. Soc., 2010, 132, 1474-1475.
Several Pd-catalyzed oxidative cyclizations proceed in excellent yield under simple aerobic conditions. Importantly, this system provided entry into enatioselective catalysis with a readily available Pd-sparteine complex.
R. M. Trend, Y. K. Ramtohul, E. M. Ferreira, B. Stoltz, Angew. Chem. Int. Ed., 2003, 42, 2892-2895.
Heterogeneous gold catalysts were easily assembled from readily available silica materials and gold complexes. Dramatic enhancement in regio- and enantioselectivity was observed when compared to the homogeneous unsupported gold catalysts in various reactions where protodeauration is the rate-limiting step. The catalysts can be recovered and recycled up to 11 times without loss of enantioselectivity.
X.-Z. Shu, S. C. Nguyen, Y. He, F. Oba, Q. Zhang, C. Canlas, G. A. Somorjai, A. P. Alivisatos, F. D. Toste, J. Am. Chem. Soc., 2015, 137, 7083-7086.
In the presence of CuI/trans-N,N′-dimethylcyclohexane-1,2-diamine as catalyst, a number of carboxylic acids underwent efficient intramolecular O-vinylation with vinyl bromides leading to the corresponding five- and six-membered enol lactones. The same catalytic system also enabled an efficient cycloisomerization of alkynoic acids.
C. Sun, Y. Fang, S. Li, Y. Zhang, Q. Zhao, S. Zhu, C. Li, Org. Lett., 2009, 11, 4084-4087.
In the presence of a cyclometalated iridium catalyst modified by (−)-TMBTP, catalytic C-C coupling of acrylic ester with alcohols provides enantiomerically enriched 5-substituted α-exo-methylene γ-butyrolactones. Bromination of the methylene butyrolactone products followed by zinc-mediated reductive aldehyde addition provides the disubstituted α-exo-methylene γ-butyrolactones with very good levels of diastereoselectivity.
T. P. Montgomery, A. Hassan, B. Y. Park, M. J. Krische, J. Am. Chem. Soc., 2012, 134, 11100-11103.
A general, efficient, and convenient cyclization of alkynes bearing carboxylic acids to the corresponding γ-alkylidene-γ-butyrolactones in the presence of commercially available Au2O3 shows a high degree of chemo-, regio-, and stereoselectivity. The 5-exo mode of cyclization and anti auration are a general trend for the Au2O3 catalyst.
P. Y. Toullec, E. Genin, S. Antoniotti, J.-P. Genęt, V. Michelet, Synlett, 2008, 707-711.
A highly efficient gold-catalyzed cyclization reaction of various functionalized acetylenic leads to γ-lactones in good to excellent yields. The reaction conditions are compatible with several functional groups, such as ester, alkene, alkyne, chloro, and free or protected alcohol.
E. Genin, P. Y. Toullec, S. Antioniotti, C. Brancour, J.-P. Genęt, V. Michelet, J. Am. Chem. Soc., 2006, 128, 3112-3113.
Imidazolinium-derived carbenes catalyze an efficient ring-expansion lactonization of oxacycloalkane-2-carboxaldehydes to give various functionalized five-, six-, and seven-membered lactones under mild reaction conditions. The electronic nature of the carbene catalyst plays a crucial role for the success of this method.
L. Wang. K. Thai, M. Gravel, Org. Lett., 2009, 11, 891-893.
A mechanistic investigation on the effect of substrate on stereoselectivity in the triflic acid-catalyzed allylboration reaction between 2-alkoxycarbonyl allylboronates and aldehydes confirms the involvement of a carbocation intermediate as the source of stereochemical inversion. This methodology allows a facile access to β,γ-disubstituted five-membered ring lactones.
T. G. Elford, Y. Arimura, S. H. Yu, D. G. Hall, J. Org. Chem., 2007, 72, 1276-1284.
Depending on the strength of a Lewis or Brřnsted acid catalyst, borate intermediates resulting from the crotylboration of aliphatic aldehydes with ester-containing crotylboronates form either γ-substituted-α-alkylidene-γ-butyrolactones via oxonia cope rearrangement-lactonization or β,γ-disubstituted-α-methylene-γ-butyrolactones via lactonization.
P. V. Ramachandran, D. Pratihar, Org. Lett., 2007, 9, 2087-2090.
The dynamic kinetic resolution of β-aryl α-keto esters using a newly designed (arene)RuCl(monosulfonamide) transfer hydrogenation catalyst generates three contiguous stereocenters with remarkable diastereoselectivity through a reduction/lactonization sequence. The resulting enantioenriched, densely functionalized γ-butyrolactones are of high synthetic utility.
K. M. Steward, E. C. Gentry, J. S. Johnson, J. Am. Chem. Soc., 2012, 134, 7329-7332.
The Reformatsky reaction of α-hydroxy ketones with indium enolates furnished highly diastereoselective lactones, while α-alkoxy ketones gave acyclic esters in moderate selectivities. A boat-type of chelated bicyclic transition state involving highly diastereoselective construction of three contiguous stereogenic centers is proposed.
S. A. Babu, M. Yasuda, Y. Okabe, I. Shibata, A. Baba, Org. Lett., 2006, 8, 3029-3032.
Treatment of 3-[(alkoxycarbonyl)alkyl]-substituted conjugated cycloalkenones with diisobutylaluminum hydride at -78 °C followed by acid quenching furnishes spiro ethers, whereas the corresponding 3-(carboxyalkyl)-substituted cycloalkenones generate spiro lactones upon reaction with sodium borohydride at 30 °C followed by acid quenching.
M.-C. P. Yeh, Y.-C. Lee, T.-C. Young, Synthesis, 2006, 3621-3624.
A mild, enantioselective hetero-Diels-Alder (HDA) reaction of the Brassard diene with aldehydes in the presence of a chiral titanium(IV) tridentate Schiff-base complexe has been developed. The mechanism is discussed.
Q. Fan, L. Lin, J. Liu, Y. Huang, X. Feng, Eur. J. Org. Chem., 2005, 3542-3552.
After NHC-catalyzed activation of acetic esters, the catalytically generated triazolium enolate intermediates serve as two-carbon nucleophiles that undergo highly enantioselective reactions with enones and α,β-unsaturated imines to give α-unsubstituted δ-lactones and lactams, respectively.
S. Chen, L. Hao, Y. Zhang, B. Tiwari, Y. R. Chi, Org. Lett., 2013, 15, 5822-5825.
An AgOTf-catalyzed intramolecular cyclization of phenoxyethynyl diols affords multisubstituted α,β-unsaturated-γ-lactones in good yields under mild conditions. This method was also applicable to the synthesis of α,β-unsaturated-δ-lactones. Replacement of AgOTf with a stoichiometric amount of N-bromosuccinimide furnishes α-bromo-substituted α,β-unsaturated lactones.
M. Egi, Y. Ota, Y. Nishimura, K. Shimizu, K. Azechi, S. Akai, Org. Lett., 2013, 15, 4150-4153.
An N-Heterocyclic carbene (NHC)-catalyzed highly enantioselective lactonization of modified enals with enolizable aldehydes proceeds via α,β-unsaturated acylazolium intermediates and yields synthetically important 4,5-disubstituted dihydropyranones.
S. R. Yetra, T. Kaicharla, S. S. Kunte, R. G. Gonnade, A. T. Biju, Org. Lett., 2013, 15, 5202-5205.
The Brřnsted acid catalyzed formal insertion of an isocyanide into a C-O bond of various acyclic and cyclic acetals can be applied to form α-alkoxy imidates. Functional groups, such as nitro, cyano, halogen, ester, and alkoxy groups, are tolerant to the reaction conditions employed. The course of the reaction is highly dependent on the structure of the isocyanide.
M. Tobisu, A. Kitajima, S. Yoshioka, I. Hyodo, M. Oshita, N. Chatani, J. Am. Chem. Soc., 2007, 129, 11431-11437.
An effective Pd-catalyzed hydroesterification of alkenylphenols with phenyl formate as CO surrogate enables the synthesis of various lactones in generally high yields with high regioselectivities. In one case, 76% ee is obtained with a chiral ligand.
H. Wang, B. Dong, Y. Wang, J. Li, Y. Shi, Org. Lett., 2014, 16, 186-189.
Pd(II)-catalyzed C-H activation of phenylacetic acids followed by an intramolecular C-O bond formation afforded benzofuranones. A modified reaction provides the first example of enantioselective C-H functionalizations through Pd(II)/Pd(IV) redox catalysis.
X.-F. Cheng, Y. Li, Y.-M. Su, F. Yin, J.-Y. Wang, J. Sheng, H. U. Vora, X.-S. Wang, J.-Q. Yu, J. Am. Chem. Soc., 2013, 135, 1236-1239.
A metal-free tandem Friedel-Crafts/lactonization reaction to 3,3-diaryl or 3-alkyl-3-aryl benzofuranones is catalyzed by HClO4. The reaction of various tertiary α-hydroxy acid esters with substituted phenols affords the desired products in rich diversity. 1H NMR studies supports that this tandem reaction proceeds via tandem Friedel-Crafts/lactonization sequence.
L. Chen, F. Zhou, T.-D. Shi, J. Zhou, J. Org. Chem., 2012, 77, 4354-4362.
A convenient radical oxidative cyclization mediated by N-iodosuccinimide (NIS) enables the synthesis of a series of dibenzopyranones from a wide scope of 2-arylbenzoic acids. The methodology offers good functional group tolerance and mild reaction conditions without the use of transition metals.
P. Gao, Y. Wei, Synthesis, 2014, 46, 343-347.
A quinine tethered Co(III)-salen complex promotes as a Lewis acid-Lewis base (LA*-LB*) bifunctional catalyst a rapid asymmetric [2+2] cycloaddition reaction between ketene and aldehydes to produce C4-substituted β-lactones in uniformly >99% ee and high isolated yields.
S. Chidara, Y.-M. Lin, Synlett, 2009, 1675-1679.
Chiral N-hetereocyclic carbenes are efficient catalysts for the formal [2 + 2] cycloaddition reactions of alkyl(aryl)ketenes with 2-oxoaldehydes to afford highly substituted β-lactones in high yields with good diastereoselectivities and excellent enantioselectivities. Both alkyl(aryl)ketenes and diarylketene worked well in this reaction.
L. He, H. Lv, Y.-R. Zhang, S. Ye, J. Org. Chem., 2008, 73, 8101-8103.
The regioselective opening of Bn2N-α-methylserine-β-lactone with organocuprates gave enantiopure α-methyl amino acids in excellent yields.
N. D. Smith, A. M. Wohlrab, M. Goodman, Org. Lett., 2005, 7, 255-258.
A new Pd-catalyzed oxidation reaction for the stereospecific conversion of enynes into cyclopropyl ketones proceeds with net inversion of geometry with respect to the starting olefin. This result is consistent with a mechanism in which the key cyclopropane-forming step involves nucleophilic attack of a tethered olefin onto the PdIV-C bond.
L. L. Welbes, T. W. Lyons, K. A. Cychosz, M. S. Sanford, J. Am. Chem. Soc., 2007, 129, 5836-5837.