Assessing architectural evolution: A case study

This is the post-print version of the Article. The official published can be accessed from the link below - Copyright @ 2011 SpringerThis paper proposes to use a historical perspective on generic laws, principles, and guidelines, like Lehman’s software evolution laws and Martin’s design principles, in order to achieve a multi-faceted process and structural assessment of a system’s architectural evolution. We present a simple structural model with associated historical metrics and visualizations that could form part of an architect’s dashboard. We perform such an assessment for the Eclipse SDK, as a case study of a large, complex, and long-lived system for which sustained effective architectural evolution is paramount. The twofold aim of checking generic principles on a well-know system is, on the one hand, to see whether there are certain lessons that could be learned for best practice of architectural evolution, and on the other hand to get more insights about the applicability of such principles. We find that while the Eclipse SDK does follow several of the laws and principles, there are some deviations, and we discuss areas of architectural improvement and limitations of the assessment approach

Synthesis of 3,3-dimethylazetidine-2-carboxylic acid and some derivatives.

γ-Chloro-α-(N-alkylimino)esters were reduced by sodium cyanoborohydride in methanol in the presence of acetic acid with complete selectivity to give rise to either γ-chloro-α-(N-alkylamino)esters (reaction at 0°C) or 1-alkyl-3,3-dimethylazetidine-2-carboxylic esters (reaction at reflux). The isolable γ-chloro-α-(N-alkylamino)esters are suitable sources for I-(N-alkylamino)-2,2-dimethylcyclopropane-1-carboxylic esters via base-induced 1,3-dehydrochlorination, while the former substrates as transient species undergo 1,4-dehydrochlorination to the corresponding azetidines. The latter process was used for the synthesis of 3,3-dimethylazetidine-2-carboxylic acid, a new non-proteinogenic sterically hindered α-amino acid, via hydrogenolysis of methyl 1-benzyl-3,3-dimethylazetidine-1-carboxylate and subsequent acidic hydrolysis. Reduction of alkyl 4-chloro-3,3-dimethyl-α-(N-alkylimino)butanoates with lithiumaluminiumhydride in diethyl ether afforded 1-alkyl-3,3-dimethyl-2-(hydroxymethyl)-azetidines.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Synthesis and reactions of 1-Amino-2, 2-dialkylcyclopropane-1-carbonitriles and -carboxamides: potential precursors of ACC derivatives

The direct cyclization of 2-amino-4-chloro-3,3-dimethylbutanenitrile with potassium tert-butoxide in THF afforded 1-amino-2,2-dimethylcyclopropane-1-carbonitrile and a dimerization product. Various new cis- and trans-1-(teri-butylamino)-2-benzyl- 2-methylcyclopropane-carbonitriles and the corresponding cyclopropanecarboxamides have been synthesized, with focus on the isolation of the pure stereoisomeric cyclopropanecarboxamides. The relative configuration of the stereoisomers was established by X-ray crystallographic analysis of one of the model compounds. A new route to the latter functionalized cyclopropanes was developed by reaction of 1-methoxycyclopropylamines with potassium cyanide. Some remarkable rearrangements of 1-aminocyclopropane-1-carbonitriles into azetidine and oxazine derivatives via Favorskii-derived intermediates are reported. Various aspects of the chemistry of geminally functionalized cyclopropanes are discussed