## Introduction  
The synthesis of optically active \(\alpha\)-amino acids using simple and easily scalable procedures is an important synthetic challenge due to their industrial interest [1]. Amongst all the reported methodologies, the enantioselective synthesis of \(\alpha\)-amino acids employing easily available and re usable chiral catalysts presents clear synthetic advantages for large-scale procedures. Particularly, the phase-transfer catalysis (PTC) [2] methodology applied to the asymmetric alkylation of glycine and alanine Schiff bases is the most simple and easy to scale up. Thus, _N_-arylmethyl substituted _Cinchona_ alkaloid-derived ammonium salts such as cinchonidine derivatives of the type **1** have been employed as chiral phase-transfer catalysts [3] in the asymmetric alkylation of iminic glycinates, first by [PERSON] [4] (**1**, R = H, Ar = Ph, X = Cl) and then by [PERSON] [5] (**1**, R = allyl, Ar = 9-anthryl, X = Br) and [PERSON] [6] (**1**, R = H, Ar = 9-anthryl, X = Cl). Interestingly, an opposite sense of the asymmetric induction can be observed changing the alkaloid moiety from cinchonidine [(_S_)-enantioselectivity] to its so-called _pseudoantioner_ cinchonine [(_R_)-enantioselectivity] [7]. Moreover, dimeric [8], trimeric [9] and even dendrimic [10]_Cinchona_ alkaloid-derived catalysts, as well as non-_Cinchona_-derived species such as spiroammonium [11] and phosphonium salts [12], TADDOL [13a,b] and other tartaric acid derivatives [13c,d], guanidinium salts [13e], binaphthyl-derived amines [13b,14] and salen-metal complexes [15] have also been used in these kinds of asymmetric PTC alkylations.  
Attaching the chiral catalyst to a solid support can be considered a next step in the development of the PTC methodology due to the resulting ease of separation and possible recycling. As a result, the preparation and uses of all kind of supported reagents is considered nowadays a fast developing topic [16]. Polymeric _Cinchona_ alkaloids have been previously used as catalysts [3] in other processes such as asymmetric Michael addition [17], dihydroxylation [18] and aminohydroylation [19] reactions. However, the use of polymeric _Cinchona_ alkaloid-derived ammonium salts as PTC catalysts for the asymmetric synthesis of \(\alpha\)-amino acid derivatives is very recent and limited. Thus, _N_-supported Merrifield resin-derived ammonium salts **2** (n = 1, R = H, X = Cl [20]; n = 4, 6 or 8, R = H, OMe, X = I [21]) from cinchonidine and quinine (R = OMe) have been prepared, as well _O_-supported polymeric derivatives such as **3**[22] (R = H, OMe, Ar = 9-anthryl) and _N_- and _O_-alkylated polyethylene glycol (PEG) monomethyl ether ammonium salt derivatives such as **4**[23a] (R = H, OMe, Ar = 9-anthryl) and **5** [R = H, OMe, Ar = 9-anthryl, oblong circle = MeOPEG\({}_{5000}\)O\({}_{2}\)C- [23a]; R = H, Ar = 9-anthryl, oblong circle = MeOPEG\({}_{5000}\)O-C\({}_{6}\)H\({}_{4}\)-(CH\({}_{2}\))\({}_{3}\)O- [23b] ], respectively. In addition, a quinine-derived _N_-methylammonium salt attached to a PEG chain at the 6-position of the quinoleine nucleus has been prepared [23b]. All these polymers have being used for the asymmetric alkylation of glycinate amines.  
In this context, and as part of our ongoing studies towards the synthesis of easily recoverable and reusable PTC catalysts for the asymmetric synthesis of \(\alpha\)-amino acids [8b,10,20c], we describe in this paper the preparation of a series of ammonium salts derived from alkaloids such as cinchonidine (**6**), quinine (**7**) and _N_-methylephreine (**8**), supported mainly at the nitrogen to an array of commercially available or easily prepared polymers, as well as their use as chiral catalysts in the model asymmetric benzylation reaction of a _N_-(diphenylmethylene)glycine ester under PTC conditions.