Programmed cell death-1 (PD-1) is an inhibitory receptor and plays an important role in the regulation of ab T cells. Little is known, however, about the role of PD-1 in cd T cells. In this study, we investigated the expression and function of PD-1 in human cd T cells. Expression of PD-1 was rapidly induced in primary cd T cells following antigenic stimulation, and the PD-1 1 cd T cells produced IL-2. When PD-1 1 cd T cells were stimulated with Daudi cells with and without programmed cell death ligand-1 (PD-L1) expression, the levels of IFN-c production and cytotoxicity in response to PD-L1 1 Daudi cells were diminished compared to the levels seen in response to PD-L1 À Daudi cells. The attenuated effector functions were reversed by anti-PD-L1 mAb. When PD-1 1 cd T cells were challenged by PD-L1 1 tumors pretreated with zoledronate (Zol), which induced cd TCR-mediated signaling, the resulting reduction in cytokine production was only slight to moderate compared to the reduction seen when PD-1 1 cd T cells were challenged by PD-L1 À tumors. In addition, cytotoxic activity of PD-1 1 cd T cells against Zol-treated PD-L1 1 tumors was comparable to that against Zol-treated PD-L1 À tumors. These results suggest that TCR triggering may partially overcome the inhibitory effect of PD-1 in cd T cells.Keywords: cd T cells . Phosphoantigen . PD-1 . PD-L1 . Tumor Supporting Information available online IntroductionHuman Vg2Jg1.2Vd2 (also termed Vg9JPVd2)-bearing gd T cells recognize the so-called phosphoantigens, a group consisting of isopentenyl pyrophosphate (IPP) and related metabolites derived from microbial pathogens in a gd TCR-dependent manner [1][2][3][4]. One of the most potent naturally occurring phosphoantigens is (E)-4-hydroxy-3-methylbut-2-enyl pyrophosphate (HMB-PP), which is derived from the 2-C-methy-D-erythritol-4-phosphate/ 1-deoxy-D-xylulose-5-phosphate pathway, an isoprenoid-biosynthetic pathway unique to certain microbes and plants [5,6]; we and others have previously reported that the subset of gd T cells [7,8]. A growing body of evidence shows that N-BPs inhibit farnesyl pyrophosphate synthase downstream of IPP in the mammalian mevalonate pathway [9,10]. It has been suggested that the resulting intracellular accumulation of IPP in the tumor cells allows gd T cells to recognize the tumor cells [11,12], although the exact mechanisms whereby this may occur remain to be identified. An increase in intracellular IPP may also occur spontaneously in certain tumor cells [13,14]. Based on these results, it has been proposed that gd T cells may be involved in surveillance for cellular metabolic stress [15,16]. Activated gd T cells produce various cytokines including IFN-g and TNF-a and also exhibit potent cytotoxic activity [17,18], and thus may serve as potential effector cells against tumors [19]. The membrane protein known as programmed cell death-1 (PD-1) is a member of the immunoglobulin superfamily, which is induced in ab T cells following antigenic stimulation [20]. Upon engagement with its specific ligan...

Experimental procedure for preparation of catalyst 1b and its characterization data: S2.Characterization data of catalysts 1c-i: S4.The results of Petasis-type reaction of 2a, 2b and 3 with 4A using catalysts 1a-i: S6.General procedure for Petasis-type reaction of 2a-f: S7.Characterization data of obtained compounds 5a-6aF: S7.Conversion of the adduct 6aC to (+)-galipinine 7 and characterization data: S10.

The first asymmetric synthesis of alpha-amino acids based on diastereoselective carbon radical addition to glyoxylic imine derivatives is reported. The addition of an isopropyl radical, generated from i-PrI, Bu(3)SnH, and Et(3)B in CH(2)Cl(2) at 25 degrees C, to achiral glyoxylic oxime ether 1 proceeded regioselectively at the imino carbon atom of the oxime ether group to give an excellent yield of the C-isopropylated product 2. The competitive reaction using glyoxylic oxime ether 1 and aldoxime ether 4 showed that the reactivity of the glyoxylic oxime ether toward nucleophilic carbon radicals was enhanced by the presence of a neighboring electron-withdrawing substituent. Thus, the alkyl radical addition to glyoxylic oxime ether 1 proceeded smoothly even at -78 degrees C, in contrast to the unactivated aldoxime ether 4. A high degree of stereocontrol in the carbon radical addition to the glyoxylic oxime ether was achieved by using Oppolzer's camphorsultam as a chiral auxiliary. The stannyl radical-mediated reaction of the camphorsultam derivative 6 with an isopropyl radical at -78 degrees C afforded a 96:4 diastereomeric mixture, 7a, of the C-isopropylated product. The reductive removal of the benzyloxy group of the major diastereomer (R)-7a, by treatment with Mo(CO)(6) and the subsequent removal of the sultam auxiliary by standard hydrolysis, afforded the enantiomerically pure D-valine (R)-12 without any loss of stereochemical purity. To evaluate the new methodology, a variety of alkyl radicals were employed in the addition reaction which gave the alkylated products 7 with excellent diastereoselectivity, allowing access to a wide range of enantiomerically pure natural and unnatural alpha-amino acids. Even in the absence of Bu(3)SnH, treatment of 6 with alkyl iodide and Et(3)B at 20 degrees C gave the C-alkylated products 7 with moderate diastereoselectivities. The use of Et(2)Zn as a radical initiator, instead of Et(3)B, was also effective for the radical reaction. The enantioselective isopropyl radical addition to 1 using (R)-(+)-2, 2'-isopropylidenebis(4-phenyl-2-oxazoline) and MgBr(2) gave excellent chemical yield of the valine derivative 2 in 52% ee.

Transition-metal-catalyzed asymmetric allylic substitution is a useful reaction in organic synthesis. [1] In the reaction with symmetric C nucleophiles such as dialkyl malonates, good yields and high enantioselectivities can now be obtained with an appropriate combination of a transition metal and a chiral ligand. [2][3][4][5] In contrast to the symmetric C nucleophiles, allylic substitution of 3-substituted allylic alcohols B with unsymmetrical C nucleophiles A is a tough and challenging task, because regio-, diastereo-, and enantioselectivities must be controlled (Scheme 1). In the last few years, research has focused on finding catalysts and chiral ligands that favor the formation of branched chiral products D and E in the allylic substitution of a-amino esters A with B.[ 6, 7] We have already reported Pd-mediated asymmetric allylic alkylation of diphenylimino glycinate 1 with several allylic acetates in the presence of the chiral phase-transfer catalyst (PTC) 6 to give the chiral products C with high enantioselectivity (up to 97 % ee).[6a] In contrast to the palladium catalyst, some transition metals, such as Ir, [3] Mo, [4] and W, [5] promote allylic alkylation at the more highly substituted terminus of the allylic substrate. Trost et al. recently reported that Mocatalyzed asymmetric allylic alkylation with azlactones occurs at the more substituted terminus with high regio-, diastereo-, and enantioselectivity.[8] However, there are no reports concerning the asymmetric synthesis of both diastereomers D and E as major products from the same starting materials and the same chiral ligand. We report here the first enantioselective allylic substitutions of 1 catalyzed by an iridium complex of chiral phosphite 10, and the diastereoselective synthesis of the products 4 and 5 by simply switching the base employed (Scheme 2).Our previous work prompted us to examine PTC 6 as a chiral catalyst in Ir-catalyzed allylic substitutions (Table 1). We first carried out the Ir-catalyzed reaction of 1 and benzoate 2 a in the presence of the chiral PTC 6, 50% KOH, [{IrCl(cod)} 2 ] (cod = cyclooctadiene), and (PhO) 3 P (entry 1). The reaction was complete after 8 h at room temperature and gave the branched products 4 a and 5 a as major products (40 % yield, 4 a:5 a = 75:25) but with low enantioselectivity (46 % ee). We next examined the effect of chiral ligands 7-10[9] in place of chiral PTC 6 on the enantioselectivity. The reaction of 1 with 2 a was carried out in the presence of 50 % KOH (3 equiv), [{IrCl(cod)} 2 ] (10 mol %), and chiral phosphites (20-40 mol %). In all cases, no linear product could be detected. Indeed, the Scheme 1. Transition-metal-mediated asymmetric allylic substitution.Scheme 2. Ir-catalyzed asymmetric allylic substitution of 1 with 2 a, a'. Table 1: Ir-catalyzed asymmetric allylic substitution of 1 and 2 a, a' with chiral PTC 6 or various chiral ligands 7-10. [c]

The viability of the iridium complex of pybox as chiral catalyst in allylic substitutions and the enantioselective synthesis of branched products was studied. Among several chiral ligands evaluated, the iridium complex of pybox having a phenyl group catalyzed the reaction with high activity to form the branched amines with good enantioselectivities when hydroxylamine, amine, and aniline were employed as a nucleophile. The allylic substitution with oximes proceeded smoothly to give the branched oxime ethers with good enantioselectivities. [reaction: see text]

Novel bifunctional organocatalysts, which possess a thiourea moiety and an amino group, were designed and synthesized. We discovered that bifunctional thiourea bearing a tertiary amino group significantly accelerated several nucleophilic addition reactions of active methylene compounds to electron-deficient double bonds. In these reactions, the double hydrogen-bonding activation of electrophiles bearing nitro, imide, and carbamate groups by the thiourea moiety and simultaneous deprotonation of nucleophiles by the dimethylamino group of bifunctional thiourea proved to play a crucial role for enhancing both reaction rate and enantioselectivity. We have demonstrated the utility of PEG-bound thiourea as a homogeneous catalyst. Although the reaction rate was somewhat decreased with PEG-bound thiourea, immobilization to a PEG support proved to facilitate the recovery and reuse of thiourea catalyst without affecting the chemical yield and enantioselectivity. A newly designed thiourea catalyst provided sufficient activation of organoboronic acids to facilitate the enantioselective Petasis transformation of quinolines even at low temperatures. A high degree of stereocontrol was achieved in the reaction of various quinolines and organoboronic acids by using a combination of H 2 O and NaHCO 3 as additives.

The efficient total synthesis of (−)-balanol, a potent inhibitor of the protein kinase C, is described. (−)-Balanol consists of a chiral hexahydroazepine-containing fragment and a benzophenone fragment, both of which were prepared via novel synthetic routes. The hexahydroazepine fragment was prepared in racemic form through either Bu3SnH- or SmI2-promoted radical cyclization of oxime ethers 2ab intramolecularly connected with the formyl group. SmI2-promoted radical cyclization of 2b was found to be particularly successful in the selective synthesis of the seven-membered trans-amino alcohol 8b. Preparation of the enantiomerically pure hexahydroazepine-containing fragment was achieved through the enantioselective enzymatic acetylation of racemic alcohol 9, employing the immobilized lipase from Pseudomonas sp. The benzophenone fragment was prepared in short steps through a biomimetic oxidative anthraquinone ring cleavage starting from commercially available natural chrysophanic acid 15c. This reaction proceeded via [4 + 2]-cycloaddition of singlet oxygen to anthracene derivative 17c, followed by Baeyer−Villiger-type rearrangement of the resulting hydroperoxide to afford the benzophenone derivatives 22 and 23.

Bifunctional thiourea 1a catalyzes aza-Henry reaction of nitroalkanes with N-Boc-imines to give syn-beta-nitroamines with good to high diastereo- and enantioselectivity. Apart from the catalyst, the reaction requires no additional reagents such as a Lewis acid or a Lewis base. The N-protecting groups of the imines have a determining effect on the chirality of the products, that is, the reaction of N-Boc-imines gives R adducts as major products, whereas the same reaction of N-phosphonoylimines furnishes the corresponding S adducts. Various types of nitroalkanes bearing aryl, alcohol, ether, and ester groups can be used as nucleophiles, providing access to a wide range of useful chiral building blocks in good yield and high enantiomeric excess. Synthetic versatility of the addition products is demonstrated by the transformation to chiral piperidine derivatives such as CP-99,994.