Base-catalyzed domino reaction

In this category, chiral a,p-unsaturated ketone, levoglucosenone, undergoes a stereoselective base-catalyzed domino reaction with furfural. The reaction was performed in saturated aqueous solution of sodium bicarbonate at room temperature for 24 h. This particular process was serendipitously discovered during the production of levoglucosenone via pyrolysis of cellulose (Scheme 6.1) [6]. 

One of the first enantioselective transition metal-catalyzed domino reactions in natural product synthesis leading to vitamin E (0-23) was developed by Tietze and coworkers (Scheme 0.7) [18]. This transformation is based on a Pdn-catalyzed addition of a phenolic hydroxyl group to a C-C-double bond in 0-20 in the presence of the chiral ligand 0-24, followed by an intermolecular addition of the formed Pd-spe-cies to another double bond. 

Within this chapter, two sections are devoted to rhodium and ruthenium. The two main procedures using rhodium are first, the formation of 1,3-dipoles from diazocompounds followed by a 1,3-dipolar cycloaddition [10] and second, hy-droformylation [11], The ruthenium-catalyzed domino reactions are mostly based on metathesis [12], with the overwhelming use of Grubbs I and Grubbs 11 catalysts. 

Two Pd-catalyzed cyclizations were used for the enantioselective synthesis of (—)-cephalotoxine [109]. One-pot Pd-catalyzed domino reactions, namely intramolecular allylation of amine and HR of 256, seem to be the best path for the desired synthesis. However, attempted direct conversion of 256 to 258 with the Herrmaim complex was unsuccessful. Then selective intramolecular aminoallylation with the chiral cyclopentyl acetate occurred smoothly to give the Spiro amine 257 in 88 % yield when Pd(PPh3)4 and TMG (tetramethylguanidine) as a base were used. The cyclization proceeded with retention of stereochemistry without racemization. The next HR reaction of 257 gave the seven-membered compound 258 in 81% yield under Jeffery s conditions using the Herrmann complex as a catalyst. No transformation of 257 to 258 occurred when Pd(PPh3)4 was used. The results show that the best catalysts for the allylation and HR are different. 

Developments on rotaxane-based shutdes (2008—2010) 12COC127. Enantioselective metal-catalyzed domino reactions (2006—2011) 12ASC3347. 

See, for instances (a) S. Santra, R R. Andreana, Org. Lett. 2007, 9, 5035-5038. A one-pot, microwave-influenced synthesis of diverse small molecules by multicomponent reaction cascades, (b) M. Presset, Y. Coquerel, J. Rodriguez, Org. Lett. 2009, 11, 5706-5709. Microwave-assisted domino and multi-component reactions with cyclic acyUcetenes expeditious syntheses of oxazinones and oxazindiones. (c) W.-J. Hao, B. Jiang, S.-J. Tu, X.-D. Cao, S.-S. Wu, S. Yan, X.-H. Zhang, Z.-G. Han, F. Shi, Org. Biomol. Chem. 2009, 7,1410-1414. A new mild base-catalyzed Mannich reaction of hetero-arylamines in water highly efficient stereoselective synthesis of 3-aminoketones under microwave heating, (d) P. Nun, J. Martinez, F. Lamaty, Synthesis 2010, 2063-2068. Microwave-assisted neat procedure for the Petasis reaction. 

In the important area of transition-metal-catalyzed domino reactions, Hartwig s group has investigated a very straightforward access to tropane derivatives based on... 

Hartung CG, Breindl C, Tillack A, Beller M. A base-catalyzed domino-isomerization-hydroamination reaction-a new synthetic route to amphetamines. Tetrahedron 2000 56 (29) 5157-5162. 

Based on a transformation described by Catellani and coworkers [61], the Lautens group [62] developed a three-component domino reaction catalyzed by palladium for the synthesis of benzo annulated oxacycles 6/1-114 (Scheme 6/1.30). As substrates, these authors used a m-iodoaryl iodoalkyl ether 6/1-113, an alkene substi-... 

The most important ruthenium-catalyzed domino process is based on a metathesis reaction. Nonetheless, a few other ruthenium-catalyzed processes have been employed for the synthesis of substituted 3,y-unsaturated ketones, as well as unsaturated y-lactams and allylic amines. 

Beller and coworkers [312] have recently published a very useful domino reaction using a Ti-based Lewis acid as catalyst to prepare indoles. The new procedure consists of a titanium-catalyzed amination of a chloroalkylalkyne to give an aryl hydra-... 

N- A ry I - 3 - (ary lmethy 1 )i soxazol id i nes were prepared from O-homoallylhydroxylamines by a Pd-catalyzed domino A-arylation/carboamination process. Optimized reaction conditions used catalytic amounts of Pd(dba)2 and of the bis(phosphine) ligand Xantphos in the presence of an excess of NaO -Bu as a base in toluene. Generally, the substituted isoxazolidines such as 86 were obtained with complete diastereoselectivity and good yields <07JOC3145>. 

This reaction was modified by the replacement of CuCN with cheaper NaCN in the presence of palladium or nickel catalyst, as exemplified by the 5% Pd(PPh3)4/10% Cul catalyzed reaction and the Ni(CN)2 or NaCN/NiBr2 based reaction under microwave irradiation for aryl bromide. The latter condition is also used for the cyanation of aryl chloride with NaCN and NiBr2. In addition, this reaction has also been extended to the preparation of some Qf,)0-unsaturated nitriles. Further modifications include the copper-catalyzed domino halogen exchange-cyanation and the application of ionic liquid as reaction media. ... 

A one-pot synthesis of macrocycles by a domino three-component reaction and [3+2] cycloaddition was investigated by Zhu et aL [99]. By combining three appropriately designed simple substrates, a programmed sequence involving an a-isocyano acetamide-based three-component reaction followed by a copper-catalyzed cycloaddition of alkyne and azide took place to afford macrocycles 119 in moderate to good yields (Scheme 26). 

A new efficient route to 4,ll-dimethoxyanthra[2,3-l)]furan-5,10-dione and its novel 2-substituted derivatives was described. The scheme was based on the Pd-catalyzed cross-coupling/heterocyclization domino reactions of... 

Copper-catalyzed C—C coupHng reactions and related domino reactions based on active methylene compounds 12CAJ1488. 

Organometallic reagents are well known for 1,4-additions and can hence be utilized to catalyze domino Michael/aldol reactions. Based on a methodology published by Noyori et al. [24], the group of Feringa estabhshed a catalytic enantios-elective protocol for the synthesis of (—)-prostaglandin Ej methyl ester [25]. There,... 

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