Diastereoselective synthesis chemistry

Several reviews of P-lactam chemistry have appeared including a general survey with 407 references <99MI335>. Other reviews include discussions of thioester enolate-imine reactions , enantio- and diastereo-selective routes to azetidinones <99MI221>, the use of diazoketones in diastereoselective synthesis <99MI43>, and solid-phase and combinatorial syntheses of p-lactams <99MI955>. 

Ashton, W.T., Dong, H., Sisco, R.M., Doss, G.A., Leiting, B., Patel, R.A., Wu, J.K., Marsilio, F., Thornberry, N.A. and Weber, A.E. (2004) Diastereoselective synthesis and configuration-dependent activity of (3-substituted-cycloalkyl) glycine pyrrolidides and fhiazolidides as dipeptidyl peptidase IV inhibitors. Bioorganic at Medicinal Chemistry Letters, 14, 859-863. 

Thiazole-aldehyde synthesis Preparation of aldehydes from C-2 substituted thiazoles by thiazolyl-to-formyl conversion, see A. Dondoni, Carbohydrate synthesis via thiazoles, in Modem Synthetic Methods, R. Scheffold, ed., Verlag Helvetica Chimica Acta, Basel, 1992, p. 377 A. Dondoni, Acyclic diastereoselective synthesis using functionalized thiazoles. Routes to carbohydrates and related natural products, in New Aspects of Organic Chemistry, Z. Yoshida and Y. Ohshiro, eds., Kodansha, Tokyo, and VCH, Weinhcim, 1992, p. 105. 

Racamonde, M., Alibes, R., Figueredo, M., Font, J., and de March, P. (2008) Photochemical cycloaddition of mono-1,1-, and 1,2-disubstituted olefins to a chiral 2(5H)-furanone. Diastereoselective synthesis of (+ (-lineatin. Journal of Organic Chemistry, 73, 5944-5952. 

The HDA reaction features in a diastereoselective synthesis of c/j-2,6-disubstituted 5,6-dihydro-2//-pyrans, but this is based on the initial formation of a dihydropyran-4-one. Regio- and stereo- chemistry are controlled during the reduction to the pyranol and an ester enolate Claisen rearrangement completes the sequence <97AJC43>. 

Reproduced from Tan Y-J, Zhang Z, Wang F-J, Wu H-H, Li Q-H. Mechanochemical milling promoted solvent-free imho Diels-Alder reaction catalyzed by FeCIs diastereoselective synthesis of cis-2,4-diphenyl-1,2,3,4-tetrahydroquinolines. RSC Adv 2014 4 35635-35638, with permission from the Royal Society of Chemistry. 

Diastereoselective synthesis of biaryls is important field in organic chemistry due to a number of natural products and a significant number of drug candidates, chiral ligands and auxiliaries that are axially chiral biaryls. One can expect great results in this chemistry, concerning both new reactions and approaches, as well as more effective methodology. 

Barber JA, Staunton J, Wilkinson MR (1986) A Diastereoselective Synthesis of the Polyke-tide Antibiotic Citrinin Using Toluate Anion Chemistry. J Chem Soc Perkin Trans 1 2101... 

Wang, Q.-R, Hou, H., Hui, L., Yan, C.-G. (2009). Diastereoselective synthesis of tran -2,3-dihydrofurans with pyridinium ylide assisted tandem reaction. Journal of Organic Chemistry, 74, 7403-7406. 

Muthusamy, S., Gunanathan, C., Nethaji, M. (2004). Multicomponent reactions of diazoamides diastereoselective synthesis of mono- and bis-spirofurooxindoles. Journal of Organic Chemistry, 69, 5631-5637. 

Azetidines are compounds of interest in the field of agricultural and pharmaceutical chemistry. They are also useful as monomers and cross-linkers in polymer industry. Due to ring strain associated with it, azetidines are also useful S5mthons in organic chemistry. The common methods for S5mthesis of azetidines are cyclizations of y-amino alcohols, y-amino halides, 3-amino allenes, reactions of 1,3-dielectrophiles with amines, metal-catalyzed cyclizations in diazocarbonyls, cycloaddition reactions, and reduction of 2-azetidinones. There are several reports in literature on the S5mthesis of azetidines in aqueous media. A diastereoselective synthesis of azetidines is reported by the reaction of azazirconacyclopentane derivatives with iodine followed by treatment with aqueous potassium carbonate [26]. 

Diastereoselective and enantioselective [3C+2S] carbocyclisations have been recently developed by Barluenga et al. by the reaction of tungsten alkenylcarbene complexes and enamines derived from chiral amines. Interestingly, the regio-chemistry of the final products is different for enamines derived from aldehydes and those derived from ketones. The use of chiral non-racemic enamines allows the asymmetric synthesis of substituted cyclopentenone derivatives [77] (Scheme 30). 

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Netherton M, Fu GC (2005)Pa]ladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 Nicolaou KC, King NP, He Y (1998) Ring-Closing Metathesis in the Synthesis of EpothUones and Polyether Natmal Products. 1 73-104 Nishiyama H (2004) Cyclopropanation with Ruthenium Catalysts. 11 81-92 Noels A, Demonceau A, Delaude L (2004) Ruthenium Promoted Catalysed Radical Processes toward Fine Chemistry. 11 155-171... 

The original medicinal chemistry synthesis of ether 18 involved reaction of alcohol 10 with racemic imidate 17 in the presence of a catalytic amount of TfOH and furnished an approximately 1.1 1 mixture of 18 19 (Scheme 7.3) [1], We thought it worthwhile to reinvestigate this reaction with chiral imidate 67 in an effort to explore the diastereoselectivity of the etherification. 

The efficiency and convenience of the chiral allenylzinc reagents are demonstrated in the synthesis of subunits of several natural products. In a total synthesis of bafilomydn Vi, seven of the 13 stereogenic centers were introduced by means of allenylzinc chemistry [112]. Three centers of chirality in the C5-C11 fragment were constructed from the precursor (R)-mesylate and the (R)-aldehyde (Eq. 9.134). The TBS protecting group of the aldehyde is important for high diastereoselectivity. Four of the five stereogenic centers in the Cl 5-C25 subunit were likewise established (Eq. 9.135). 

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