Chirality-directed co-crystallization of different configurationally opposite dialkyl 2,5-diazabicyclo[2.2.2]octane-3,6-dione-1,4-dicarboxylates

Stereoregular self-assembling of diastereomeric bicyclic bis-lactam diesters

“…The main task of this work is to determine which way takes place in case of 1 and 2, either resolution of the diastereomers by crystallization or their co-crystallization. The recently found co-crystallization rather than resolution of various configurationally opposite bis-lactam diesters like B (R = Et and Me, R = Et and Pr) 4 serves as a premise for the latter way.…”

“…7 The structure and diastereomeric composition (1:1) of both products (+)-1 and (+)-2 were confirmed by 1 H and 13 C NMR spectra † (Figure 1), the parameters of which corresponded to those of analogues A, B and related co-crystals. 4 It should be noted that diastereomers a and b for both 1 and 2 differ distinctively in the 1 H NMR signals of diastereotopic protons of CH 2 O groups nearest to a chiral skeleton of diastereomers of The optical activity of (+)-1 and (+)-2 was measured by polarimetry and CD spectroscopy † (cf. ref.…”

Chirality-directed self-assembling of long-chain dialkyl 3,7-diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylates

“…Bicyclic bis-lactams of C 2 symmetry hold much promise for building supramolecular structures. [1][2][3][4][5][6][7][8] It was shown recently 6 that bis-lactam A in crystal is self-assembled into heterochiral H-bonded tapes of a diagonal zigzag type. The first similar motive of structure was reported for cyclo-di-β-alanine 3,9 and then for bis-lactams of the [2.2.2], 1,2,4,8 [3.3.0] 5 and [3.3.1] 6 series.…”