LADDERANES SYNTHESIS

DR ANTHONY MELVIN CRASTOSHORT PRESENTATION

MARCH2011

This is a vast topic and a short overview is givenand in no way complete justice can be done for this

A ladderane is an organic molecule containing two or more fused rings of cyclobutane. The name is a portmanteau because the serial cyclobutane rings look like a ladder and are singly bonded like alkanes. The chemical formula for a ladderane with n rings is C2n+2H2n+6. The geometry of ladderanes is highly strained because ligands to the carbon atoms cannot extend to their ideal angles. However, examples of ladderanes have been found in living organisms.[1] An example ispentacycloanammoxic acid[2]

 which is composed of 5 fused cyclobutane units. It is found in bacteria performing the anammox process where it forms part of a tight and very dense membrane believed to prevent the organism from losing the intermediate hydrazine which is involved in the production of nitrogen and water from nitrite ions and ammonia.[3]

A simple ladderane, consisting of three fused cyclobutane rings

Back in 2005, Corey and Mascitti prepared the first enantioselective (single mirror image of a compound) synthesis of pentacycloanammoxic acid (JACS 2006, 128,3118-3119). This C20 fatty acid, firstdiscovered in deep-sea bacteria by Dutch researchers in 2002, provides an extremely rigid lipid bilayer to bacterial cell membranes, which biologists believe shields them from their own toxic metabolic byproducts – anammoxic bacteria utilize ammonia for energy, and produce hydrazine (rocket fuel) and hydroxylamine as waste products en route to N2 and H2O.

^ a b Nouri, D H, Tantillo, D J (2006). "They Came from the Deep: Syntheses, Applications, and Biology of Ladderanes". Curr. Org. Chem. 10(16): 2055–2074. doi:10.2174/138527206778742678

.^ J. S. Sinninghe Damsté, M. Strous, W. I. C. Rijpstra, E. C. Hopmans, J. A. J. Geenevasen, A. C. T. van Duin, L. A. van Niftrik and M. S. M. Jetten (2002). "Linearly concatenated cyclobutane lipids form a dense bacterial membrane". Nature 419 (6908): 708–712.doi:10.1038/nature01128. PMID 12384695.

^ Vincent Mascitti and E. J. Corey (2006). "Enantioselective Synthesis of Pentacycloanammoxic Acid". J. Am. Chem. Soc. 128 (10): 3118.doi:10.1021/ja058370g. PMID 16522072.

Linearly concatenated cyclobutane lipids form a dense bacterial membrane

Jaap S. Sinninghe Damsté, Marc Strous, W. Irene C. Rijpstra, Ellen C. Hopmans, Jan A. J. Geenevasen, Adri C. T. van Duin, Laura A. van Niftrik and Mike S. M. Jetten

Nature 419, 708-712(17 October 2002) doi:10.1038/nature01128

Enantioselective Synthesis of Pentacycloanammoxic AcidVincent Mascitti and E. J. Corey

pp 3118–3119Publication Date (Web): February 16,

2006 (Communication)DOI: 10.1021/ja058370g

"The synthesis of the 3- and 5-ladderanes is a crowning achievement," says chemistry professor Bruce M. Foxman of Brandeis University. "The work provides both a new subclass of solid-state photocycloaddition products and an elegant example of how the careful planning and execution of a solid-state methodology may open the door to a simple, high-yield synthesis of an elusive class of molecules."

A solid-state intermolecular synthesis of ladderanes that provides gram amounts of these unusual compounds in quantitative yields has been developed by assistant chemistry professor Leonard R. MacGillivray and graduate students Tomislav Frii and the late Xiuchun Gao of the University of Iowa [Angew. Chem. Int. Ed.,43, 232 (2004)].

Ladderanes feature a series of fused cyclobutane rings that chemists believe could impart unique electronic properties or serve as spacers to separate metals or functional groups for a potential new class of optoelectronic materials. Several groups have made short ladderanes with limited success, building them up from halogenated cyclobutenes, from alkenes and alkynes, or by fusing together polyenes [Angew. Chem. Int. Ed., 42, 2822 (2003)]. One problem, MacGillivray notes, is that in solution the ladder precursors are probably too disorganized to align and react properly.

Structures of ladderane lipids derived from anammox bacteria and their transformation products derived from microbial oxic degradation. (1) C18-[5]-ladderane FA, (2) C20-[5]-ladderane FA, (3) C18-[3]-ladderane FA, (4) C20-[3]-ladderane FA, (I) C14-[5]-ladderane FA, (II) C14-[3]-ladderane FA, (III) C16-[3]-ladderane FA. Key: FA = fatty acid.

amcrasto@gmail.comDR ANTHONY CRASTOchemistry sites https://sites.google.com/site/anthonycrastoorganicchemistry/sites---my-own-on-the-net

THANKS AND REGARD'SDR ANTHONY MELVIN CRASTO Ph.Damcrasto@gmail.com

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