Reaction of [(Cp2TiCH3)(THF)+][BPh4] with Tripeptide Derivatives: Formation of Cationic (Peptide)titanocene Complexes

Abstract

A series of Z-and Boc-protected tripeptide methyl esters ] was prepared using the amino acids glycine, alanine and valine. In both the alanine and the valine series a single glycine unit was introduced and its position inside the tripeptide framework was systematically varied. Reaction of these 16 tripeptide derivatives with the organometallic reagent [Cp 2 TiCH 3 (THF) + ][BPh 4 − ] (13) resulted in the formation of methyl(peptide)titanocene cation complexes that contained the strongly electrophilic [Cp 2 TiCH 3 + ] cation moiety coordinated to a single carboxamide carbonyl oxygen atom. Mostly, the carbonyl oxygen atom of the central amino acid residue was specifically attached to yield the coordination products 5−12(coord 7 ). In a few specific cases, formation of the κO-adduct between the [Cp 2 TiCH 3 + ] cation and the Nterminal amino acid moiety was also observed, especially in the cases of the N-terminal glycine derivatives. In one case

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and indolyl-substituted titanocene anti-cancer drugs

“…The use of indolyl lithium in the synthesis of other metallocenes is well known [26][27][28][29][30], and it has recently been used for the synthesis of achiral titanocene dichlorides [13,14]. This time, the carbolithiation method led to the synthesis of a new group of titanocenes that contain stereo centres (5a-c).…”

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and indolyl-substituted titanocene anti-cancer drugs

“…The use of indolyl lithium in the synthesis of other metallocenes is well known [26][27][28][29][30], and it has recently been used for the synthesis of achiral titanocene dichlorides [13,14]. This time, the carbolithiation method led to the synthesis of a new group of titanocenes that contain stereo centres (5a-c).…”

Cationic Titanium Complexes Containing Alkoxide and Carboxylate Pincer Ligands; Noninnocent Role of the Anionic Moieties in Their Reactivity

“…Borate anions have been widely used as counterions to stabilize cationic titanium compounds. One of the most widely used synthetic strategies for the preparation of cationic complexes containing borate anions is the reaction of an alkyl complex with B(C 6 F 5 ) 3 or borates . However, it is also possible to generate these compounds through anion metathesis by reaction of a cationic complex with a borate.…”

4‐(4,6‐Dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium Toluene‐4‐sulfonate (DMT/NMM/TsO−) Universal Coupling Reagent for Synthesis in Solution

“…Product: Boc‐Ala‐Gly‐Ala‐OMe (0.268 g, 81%), oil, = −15 ( c = 1.0, MeOH), lit. = −7 ( c = 1.0, CH 2 Cl 2 ). Anal.…”

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and indolyl-substituted titanocene anti-cancer drugs

“…The use of indolyl lithium in the synthesis of other metallocenes is well known [26][27][28][29][30], and it has recently been used for the synthesis of achiral titanocene dichlorides [13,14]. This time, the carbolithiation method led to the synthesis of a new group of titanocenes that contain stereo centres (5a-c).…”

Cationic Titanium Complexes Containing Alkoxide and Carboxylate Pincer Ligands; Noninnocent Role of the Anionic Moieties in Their Reactivity

“…Borate anions have been widely used as counterions to stabilize cationic titanium compounds. One of the most widely used synthetic strategies for the preparation of cationic complexes containing borate anions is the reaction of an alkyl complex with B(C 6 F 5 ) 3 or borates . However, it is also possible to generate these compounds through anion metathesis by reaction of a cationic complex with a borate.…”

4‐(4,6‐Dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium Toluene‐4‐sulfonate (DMT/NMM/TsO−) Universal Coupling Reagent for Synthesis in Solution

“…Product: Boc‐Ala‐Gly‐Ala‐OMe (0.268 g, 81%), oil, = −15 ( c = 1.0, MeOH), lit. = −7 ( c = 1.0, CH 2 Cl 2 ). Anal.…”

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and indolyl-substituted titanocene anti-cancer drugs

“…The use of indolyl lithium in the synthesis of other metallocenes is well known [26][27][28][29][30], and it has recently been used for the synthesis of achiral titanocene dichlorides [13,14]. This time, the carbolithiation method led to the synthesis of a new group of titanocenes that contain stereo centres (5a-c).…”

Cationic Titanium Complexes Containing Alkoxide and Carboxylate Pincer Ligands; Noninnocent Role of the Anionic Moieties in Their Reactivity

“…Borate anions have been widely used as counterions to stabilize cationic titanium compounds. One of the most widely used synthetic strategies for the preparation of cationic complexes containing borate anions is the reaction of an alkyl complex with B(C 6 F 5 ) 3 or borates . However, it is also possible to generate these compounds through anion metathesis by reaction of a cationic complex with a borate.…”

4‐(4,6‐Dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium Toluene‐4‐sulfonate (DMT/NMM/TsO−) Universal Coupling Reagent for Synthesis in Solution

“…Product: Boc‐Ala‐Gly‐Ala‐OMe (0.268 g, 81%), oil, = −15 ( c = 1.0, MeOH), lit. = −7 ( c = 1.0, CH 2 Cl 2 ). Anal.…”