The weak Lewis acid HBpin was observed to couple readily with aromatic and aliphatic amines of varying bulkiness (entries 1 8), but failed to react with the very bulky HN(SiMe3)2 (entry 9).
Short- and medium-chain 2-hydroxy acids with up to ten carbon atoms (Table 5, entries 10 and 11), unsaturated cis- and trans-2-hydroxydec-4-enoic acid (Table 5, entry 14), bulky phenyllactic acid (Table 5, entry 9) and the oxa-analogue 2-hydroxy-4-pentoxybutyric acid (Table 4, entry 13) were well accepted as substrates in kinetic resolution with good to excellent ees.
However, less (entries 2 and 3) or more (entry 4) sterically bulky alcohols were all inferior to IPA, and common diols also provided no notable advantage (entries 5 7).
Breast cancer cell spheroids attached to lymphendothelial cell (LEC) monolayers were used to investigate the process of intravasation by measuring the areas of 'circular chemorepellent-induced defects' (CCID), which can be considered as entry gates for bulky tumour intravasation.
Similarly, smaller anilines coupled at rates significantly in excess of the background reactions (entry 12), while bulkier anilines reverted to the uncatalyzed rate (entries 13 and 14).
While less sterically congested alkyl amines coupled readily (entry 10), reactions with more bulky substrates (entry 11) were slower and comparable to the background reactions.
Extending the N-alkyl chain (from methyl to n-butyl and neopentyl) led to an increase in the product ee value to 88%% (Table 1, entries 4 and 5), whereas the substitution with phenyl and bulky tert-butyl groups has the opposite effect (entries 6 and 7).
The space agency has never recorded any debris from the ATV surviving re-entry, but believes that its bulky docking mechanism could theoretically remain intact.
Because bulky residues may change more than only the entry to the cavity we produced a number of control Phe-substitutions outside this region and analyzed HbpR mutant protein production in E. coli.
Body mass (kg) was measured on entry to the current study, with bulky clothing removed.
