Convergent assembly

Urbanek RA, Sabes SF, Forsyth CJ, Efficient synthesis of okadaic acid 1. Convergent assembly of the C15-C38 domain, J Am Chem Soc 120 2523—2533, 1998. 

Multicomponent reactions have recently become one of the favored methods to prepare pharmacologically important compounds. Ugi condensations with O-protected hydroxylamines have been successfully performed in THE using ZnCl2 as activating agent (Scheme 56). This synthetic strategy opens up the route to a very convergent assembly of internal hydroxamic acid derivatives (A-acyl-A-hydroxypeptides 109)" . 

Scheme 23 Highly convergent assembly of calcitriol 83 employing an alkyne-relayed inter-intramolecular carbopalladation cascade.

R. Madsen, U. E. Udodong, C. Roberts, D. R. Mootoo, P. Konradsson, and B. Fraser-Reid, Studies related to synthesis of glycophosphatidyl inositol membrane bound protein anchors Part VI. Convergent assembly of sub-units, J. Am. Chem. Soc. 777 1554 (1995). 

A clever strategy has been reported by Moroder s group. 139 During the convergent assembly of three peptide chains containing various protected forms of Cys, thiol-thiol exchange reactions lead to formation of a cysteine knot core (Scheme 17). 

Convergent assembly using a monofunctionalised AB2FG-type monomeric branching building block. Random monofunctionalisation of dendritic branches on monomeric building blocks is a necessary feature of the synthesis. 

SCHEME 13.7 Fraser-Reid s synthesis of building blocks for the convergent assembly of the rat brain Thy-1 GPI anchor. DMAP, 4-dimethylaminopyridine PPTS, pyridinium... 

Scheme 2. Convergent assembly of glycopeptides via fragment coupling...

The most recent total synthesis of thyrsiferol 23-acetate (4) was reported by Forsyth and co-workers [29]. Their work focused upon a convergent assembly of the three fragments 82, 85, and 86, illustrated in Scheme 18, offering both efficiency and practicality. 

Thompson, C. F., Jamison, T. F., Jacobsen, E. N. Total Synthesis of FR901464. Convergent Assembly of Chiral Components Prepared by Asymmetric Catalysis. J. Am. Chem. Soc. 2000, 122,10482-10483. 

Another relevant example is the convergent assembly of a biantennary heptasac-charide motif 39 of a human glycoprotein isolated from seminal plasma. It was accomplished by Ley s and Wong s groups in a 2 + 3 + 2 fashion as depicted69... 

R. Geurtsen, F. Cote, M. G. Hahn, and G.-J. Boons, Chemoselective glycosylation strategy for the convergent assembly of phytoalexin-elicitor active oligosaccharides and their photoreactive derivatives, /. Org. Chem., 64 (1999) 7828-7835. 

G.-J. Boons, S. Bowers, and D. M. Coe, Trityl ethers in oligosaccharide synthesis A novel strategy for the convergent assembly of oligosaccharides, Tetrahedron Lett., 38 (1997) 3773-3776. 

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