We report a new route to tertiary α-amino stereocenters by sequential alkylation of α-amino nitriles followed by reductive lithiation of the nitrile and cyclization onto an alkene. Reductive lithiation of α-amino nitriles using lithium 4,4′-di-tert-butylbiphenylide (LiDBB) and subsequent intramolecular carbolithiation proceeded with modest to high diastereoselectivity to deliver cyclic or spirocyclic ring systems. The stereoselectivity of these intramolecular carbolithiations was examined using density function calculations to evaluate plausible transition state models.Tertiary α-amino stereogenic centers are found in many classes of alkaloids, including the cylindricines, 1 fasicularin, 2 and pinnaic acid, 3 and these stereogenic centers are often incorporated into rings. Previously we reported the reductive lithiation and cyclization of cyanohydrins to form spirocyclic ethers, often with high stereoselectivity. 4 A similar strategy might allow complex alkaloids skeletons to be rapidly assembled from α-amino nitriles. Nitriles can be deprotonated and these anions are excellent nucleophiles for alkylation. 5 Thus the α-amino nitriles substrates might be assembled using the facile alkylation adjacent to the nitrile, and subsequent reductive lithiation would trigger and intramolecular carbolithiation reaction. Herein we describe several model studies that delineate the scope of this reductive cyclization strategy.Husson has studied the stereoselective reductive decyanation of α-amino nitriles extensively and applied this method very effectively in the synthesis of alkaloids. 6 Both Husson 7 and Grierson 8 have reported isolated examples of α-amino nitrile reduction and intramolecular alkylation, but they have not reported cyclization onto alkenes. Intramolecular cyclization of alkyllithium reagents onto unactivated alkenes has been extensively studied by Bailey 9 and by a number of other groups. 10 Wiberg and Bailey used computational methods to predict a fourcentered transition state for insertion of an alkene into the organolithium bond. 11 The classic intramolecular carbolithiation of an α-amino alkyllithium reagent was reported by Coldham using an optically pure secondary α-amino stannane to generate the alkyllithium intermediate. 12 Transmetalation of stannanes is not an effective method for the preparation of tertiary alkyllithium reagents, however, and neither is the deprotonation method commonly used for carbamate-activated α-amino alkyllithium reagent generation. 13 The poor accessibility of these reagents means that intramolecular carbolithiation reactions using tertiary α-amino alkyllithium reagents are essentially unknown. Reduction of thiophenols and of nitriles with the powerful reducing agent lithium 4,4′-di-tertbutylbiphenylide (LiDBB) 14 in THF has proven to be a general route to many unusual and complex alkyllithium reagents. 15 We recently reported that the reductive lithiation of α-amino nitriles provides a facile, and in some cases stereoselective, route to tertiary α-amino alkyllith...

Nucleocapsid 7 (NCp7) inhibitors have been investigated extensively for their role in impeding the function of HIV-1 replication machinery and their ability to directly inactivate the virus. A class of NCp7 zinc finger inhibitors, S-acyl-2-mercaptobenzamide thioesters (SAMTs), was investigated for topical drug delivery. SAMTs are inherently unstable due to their hydrolytically labile thioester bond thus requiring formulation approaches that can lend stability. We describe the delivery of N-[2-(3,4,5-trimethoxybenzoylthio)benzoyl]-β-alanine amide (SAMT-10), as a single agent antiretroviral (ARV) therapeutic and in combination with the HIV-1 reverse transcriptase inhibitor pyrimidinedione IQP-0528, from a hydrophobic polyether urethane (PEU) intravaginal ring (IVR) for a month. The physicochemical stability of the ARV-loaded IVRs was confirmed after 3 months at 40°C/75% relative humidity (RH). In vitro, 25 ± 3 mg/IVR of SAMT-10 and 86 ± 13 mg/IVR of IQP-0528 were released. No degradation of the hydrolytically labile SAMT-10 was observed within the matrix. The combination of ARVs had synergistic antiviral activity when tested in in vitro cell based assays. Toxicological evaluations performed on an organotypic EpiVaginal™ tissue model demonstrated a lack of formulation toxicity. Overall, SAMT-10 and IQP-0528 were formulated in a stable PEU IVR for sustained release. Our findings support the need for further preclinical evaluation.

The HIV-1 nucleocapsid (NCp7), structurally defined by zinc-binding domains, participates in crucial stages of the HIV-1 lifecycle and is mutationally nonpermissive, making it an attractive anti-HIV target. Mode of action studies have shown that the secondary structure and activity of NCp7 can be disrupted by acyl transfer from N-2-mercaptobenzoyl-amino amides. We have developed an improved one-pot reaction that affords N-2-mercaptobenzoyl-amino acids on multi-gram scales. This synthetic route allows for rapid modular construction and has greatly expanded the scope of easily accessible potential NCp7 inhibitors.

AMP-activated protein kinase (AMPK) is an evolutionarily conserved energy sensor. Activation of AMPK leads to a number of metabolic benefits, including improved mitochondrial function in skeletal muscle and lowering of serum glucose levels in type-2 diabetes models. However, direct activation of AMPK leads to cardiac enlargement, and an alternative strategy that activates AMPK without affecting the heart is needed. Inhibition of phosphodiesterase 4 (PDE4), which is poorly expressed in the human heart, activates AMPK in other tissues. In a screen to identify novel PDE4 inhibitors, we discovered compound CBU91, which is 5–10 fold more potent than rolipram, the best characterized PDE4 inhibitor. CBU91, like rolipram, is able to activate AMPK and Sirt1 and increase mitochondrial function in myotubes. These findings suggest that activation of AMPK in myotubes is a general property of PDE4 inhibition and that PDE4 inhibition may activate AMPK in metabolically relevant tissues without affecting the heart.