Steven H. Bertz

Branching ingraphs amd molecules

Abstract Branching at a point is defined in terms of the degrees of the central points in the star graphs, K 1, n , n =0,1,2,3,…. As atoms are added to a structure (i.e., as points are added to a graph), the new structure in which the atom has been affixed to the precursor atom with the higher degree is the more branched. A branching index consistent with this axiom is B M = B R + B s + r + s , where B M , B R , and B S are the branching indices of the new structure and two precursor structures, respectively, and r and s are the degrees of the precursor atoms before they are connected by a bond (line). If B M =0 for methane, then for other molecules it is simply equal to the number of pairs of adjacent bonds, or the number of lines in the line graph of the line graph of the molecular graph. The iterated line graphs are then used to obtain a more complete ordering. Our results are compared to those of other approaches and help clarify branching and its relation to chemical properties such as boiling point.

The preparation of lithium organocuprates from various Cu(I) salts

Abstract Various Cu(I) salts have been tested as precursors for organocuprates in side-by-side comparisons under controlled conditions. CuCN and CuBr·SMe2 appear to be superior to CuI, CuBr, and CuCl. CuSCN and CuOTf are also good precursors in some circumstances.

On the complexity of graphs and molecules

A new formula for the complexity of graphs is proposed and applied to the points lines and ‘connections’ of some chemically relevant graphs.

The synthesis of triquinacene via the weiss reaction.

Abstract A short, simple preparation of triquinacene 1 is based on four key steps: the Weiss reaction, high-yield monoalkylation of the resulting bicyclo[3.3.0] system, aldol cyclization of aldehyde 6 and HMPA-mediated dehydration of triol 8 .

The preparation of hindered cuprates from aldehyde tosylhydrazones

Abstract Copper reagents react with secondary and tertiary aldehyde tosylhydrazones to give unique, hindered cuprates which are alkylated in a one-flask procedure.

Base-Mediated Stereospecific Synthesis of Aryloxy and Amino substituted Ethyl Acrylates

The stereospecific synthesis of aryloxy and amino substituted E- and Z-ethyl-3-acrylates is of interest because of their potential in the polymer industry and in medicinal chemistry. During work on a copper-catalyzed cross-coupling reaction of ethyl (E)- and (Z)-3-iodoacrylates with phenols and N-heterocycles, we discovered a very simple (nonmetallic) method for the stereospecific synthesis of aryloxy and amino substituted acrylates. To study this long-standing problem on the stereoselectivity of aryloxy and amino substituted acrylates, a series of O- and N-substituted nucleophiles was allowed to react with ethyl (E)- and (Z)-3-iodoacrylates. Screening of different bases indicated that DABCO (1,4-diazabicyclo[2.2.2]octane) afforded successful conversion of ethyl (E)- and (Z)-3-iodoacrylates into aryloxy and amino substituted ethyl acrylates in a stereospecific manner. Herein are the details of this DABCO-mediated stereospecific synthesis of aryloxy and amino substituted E- or Z-acrylates.