Diastereoselective Lewis acid mediated hydrophosphonylation of heterocyclic imines: a stereoselective approach towards α-amino phosphonates

2,5-Dihydro-1,3-thiazoles as Scaffolds in the Synthesis of O,N-Diacyl O,N-Acetals in a One-pot Reaction

“…On account of this, the direct influence on the creation of the new stereogenic center is less important. In fact, the bulky tert-butyl group displaces the amido moiety to the opposite site [18,38]. The attack of the carboxylate occurs, therefore, evasively on the amido moiety leading predominantly to cis-configurated O,N-diacyl O,N-acetals 4.…”

“…The reason for this reaction course is the bulkiness of the phenyl group. The likewise voluminous carboxylate avoids the bulky phenyl group [18,38] and attacks from the less hindered side resulting predominantly in trans-configurated amides 3. On the other hand, the attack of the carboxylate on the N-acyliminium ions occurs cis to the tert-butyl group during the reaction to O,N-diacyl O,N-acetals 4 (Fig.…”

“…The characteristic attribute of the 2,5-dihydro- (Tables 3 and 4). Due attention needs to be paid to the fact that the configuration at the existing stereogenic center of the imines can influence the formation of the new chirality center formed in the reaction [18,38].…”

Synthetic methods of cyclic α-aminophosphonic acids and their esters

“…41 Since the chiral auxiliary might be easily removed by hydrolysis of the phosphonic ester, Schlemminger et al 42 carried out the addition of chiral BINOL-phosphite to achiral 3-thiazolines 41 in the presence of BF 3 -OEt 2 , obtaining the corresponding thiazolidinyl phosphonates 43 in moderate yield and excellent diastereoselectivity. It is noteworthy that the stereoselectivity of the BINOL-phosphite seemed to be independent of the steric demands of the nearby substituents R (Scheme 16).…”

Conformation of Sterically Hindered 4-Methyl-2-oxo-2-trityl-1,3,2-dioxaphosphorinane in the Solid State and the Solution

“…Among these the posphonate moiety is an important pharmacophore in the pharmaceutical chemistry [1][2][3][4][5][6] and can be used as a building block for antibiotics [7][8][9][10], herbicides [11,12], insecticides [13], fungicides [14] and anti-viral agents [15]. Additionally, the phosphonic acids and their derivatives may be considered as long life analogues of transition states for tetrahedral intermediates in amide/ester hydrolysis [16].…”