Sarah Weinman

Trans-1,4,5,8-tetracarboethoxy- and 1,4,5,8-tetramethyl- 1,4,5,8-tetraazadecalin (tad) ☆ ☆☆

Abstract Chemical correlation between the title compounds ( 7 and 8 ) was performed. X-ray crystallographic analysis of the novel tetraurethane ( 7 ) proved the trans configuration of ( 7 ) and indirectly that of tetramethyl TAD ( 8 ). The latters chemical and conformational behavior is examined and discussed.

Oligomerization of 1,2‐Ethanedithiol: An Expedient Approach to Oligothiaethylenethioglycols

Reactions of ethylenedithioglycol (ETG) with Na(2)CO(3), K(2)CO(3), and Cs(2)CO(3) provided the oligothiaethylenethioglycols (nETG): di- (DETG), tri- (TrETG), tetra- (TETG), and pentathiaethylenethioglycol (PETG), along with higher polymers. The most efficient carbonate was K(2)CO(3) and reactions using DETG and TrETG as starting materials--or their mixtures--were also found to afford similar species. This largely unknown oligomerization process was thoroughly explored and potential pathways were put forward. A convenient conversion of ETG to laboratory quantities of the otherwise scarce and/or expensive DETG, TrETG, TETG, and PETG oligomers, in organic or aqueous media was achieved. Notably, this straightforward reaction takes place without the addition of expensive or toxic metal catalysts and with pure water as the solvent, thereby highlighting its potential as a green chemical reaction. Moreover, the process opens up new approaches to dynamic combinatorial libraries (DCLs) of oligomers and macrocycles with manifolded nETG [(SCH(2)CH(2))(n)S] bridges.

New macromolecular host systems. Preparation and structure of certain functionalized 2,6-diaryl-cis-1,3,5,7-tetraoxadecalin podand compounds and macro-m-cyclophanes

A series of new podands consisting of 2,6-cis-diaryl-1,3,5,7-tetraoxadecalin systems 2–7 have been prepared and fully characterized; the crystal structure of (2R,6R,9S; 9,10-P)-cis-2,6-di(p-nitrophenyl)1,3,5,7-tetraoxadecalin 4 showed characterized ‘host-guest’ packing and structural data which fitted well with the stereoelectronic features of the cis-1,3,5,7-tod system and a new class of macro-cyclophanes (9, 10) was unravelled.

Novel bromination reagents. Electrophilic aromatic bromination by hexabromocyclopentadiene

Hexabromocyclopentadiene efficiently and regioselectively brominates activated aromatic compounds, in a process which is interpretde as involving ready formation of the pentabromocyclopentadienide anion by bromonium ion release.

Unusual photorearrangements of homoconjugated diacylcyclohexa-2,4-dienes

The unprecedented triplet sensitized electrocyclic ring opening of various 3a,7a-diacyl-3a,7a-dihydroindans (3)–(5) to the corresponding cyclononatriene derivatives (7)–(11) is reported, direct irradiation at all absorbing wavelengths of the keto-ester (5) resulting in a diastereoselective oxa-di-π-methane (ODPM) rearrangement to the tricyclic product (6); dimethyl 1,2-dimethyl-1,2-dihydrophthalate (15) reacted similarly to give dimethyl E,E,E-2,7-dimethyl-2,4,6-octatrienoate (16), whose structure has been determined by single crystal X-ray diffraction analysis.