Macrocyclization via remote meta-selective C-H olefination using a practical indolyl template.

The synthesis of macrocyclic compounds with different sizes and linkages remains a great challenge via transition metal-catalysed intramolecular C-H activation. Herein, we disclose an efficient macrocyclization strategy via Pd-catalysed remote meta-C-H olefination using a practical indolyl template. This approach was successfully employed to access macrolides and coumarins. In addition, the intermolecular meta-C-H olefination also worked well and was exemplified by the synthesis of antitumor drug belinostat from inexpensive and readily available benzenesulfonyl chloride. Notably, catalytic copper acetate and molecular oxygen were used in place of silver salts as oxidants. Furthermore, for the first time, the formation of a macrocyclophane cyclopalladated intermediate was detected through in situ Fourier-transform infrared monitoring experiments and ESI-MS.

Differentiation and functionalization of remote C-H bonds in adjacent positions.

Site-selective functionalization of C-H bonds will ultimately afford chemists transformative tools for editing and constructing complex molecular architectures. Towards this goal, it is essential to develop strategies to activate C-H bonds that are distal from a functional group. In this context, distinguishing remote C-H bonds on adjacent carbon atoms is an extraordinary challenge due to the lack of electronic or steric bias between the two positions. Herein, we report the design of a catalytic system leveraging a remote directing template and a transient norbornene mediator to selectively activate a previously inaccessible remote C-H bond that is one bond further away. The generality of this approach has been demonstrated with a range of heterocycles, including a complex anti-leukaemia agent and hydrocinnamic acid substrates.

Hemilabile Benzyl Ether Enables γ-C(sp3)-H Carbonylation and Olefination of Alcohols.

Pd-catalyzed C(sp3)-H activation of alcohol typically shows ß-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct γ- or δ-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of ß-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.

Palladium(II)-Catalyzed Site-Selective C(sp3 )-H Alkynylation of Oligopeptides: A Linchpin Approach for Oligopeptide-Drug Conjugation.

The palladium(II)-catalyzed C(sp3 )-H alkynylation of oligopeptides was developed with tetrabutylammonium acetate as a key additive. Through molecular design, the acetylene motif served as a linchpin to introduce a broad range of carbonyl-containing pharmacophores onto oligopeptides, thus providing a chemical tool for the synthesis and modification of novel oligopeptide-pharmacophore conjugates by C-H functionalization. Dipeptide conjugates with coprostanol and estradiol were synthesized by this method for potential application in targeted drug delivery to tumor cells with overexpressed nuclear hormone receptors.

Site-selective C(sp3)-H functionalization of di-, tri-, and tetrapeptides at the N-terminus.

Although the syntheses of novel and diverse peptides rely mainly on traditional coupling using unnatural amino acids, postsynthetic modification of peptides could provide a complementary method for the preparation of nonproteinogenic peptides. Site selectivity of postsynthetic modification of peptides is usually achieved by targeting reactive moieties, such as the thiol group of cysteine or the C-2 position of tryptophan. Herein, we report the development of site-selective functionalizations of inert C(sp(3))-H bonds of N-terminal amino acids in di-, tri-, and tetrapeptides without installing a directing group. The native amino acid moiety within the peptide is used as a ligand to accelerate the C-H activation reaction. In the long run, this newly uncovered reactivity could provide guidance for developing site-selective C(sp(3))-H activation toward postsynthetic modification of a broader range of peptides.

Elevation of serum procalcitonin in patients after chemical pleurodesis with intrapleural injection of OK-432.

INTRODUCTION: In patients with refractory pleural effusion or pneumothorax, fever and elevated level of white blood cell count (WBC) are frequently observed after chemical pleurodesis with intrapleural injection of OK-432, which make it difficult to differentiate whether it was from the side effects of OK-432 or concurrent bacterial infection. OBJECTIVE: Procalcitonin (PCT) levels were measured before and after pleurodesis so as to discuss whether PCT is useful for distinguishing between the side effects of OK-432 and concurrent bacterial infection. METHOD: Twenty-six patients with refractory pleural effusion or pneumothorax who underwent chemical pleurodesis with intrapleural injection of OK-432 at the First Affiliated Hospital of Sun Yat-sen University between August 2010 and August 2012 were included in our study. Levels of PCT and WBC were measured before and after pleurodesis. RESULT: Of all 26 patients, 22 patients were with refractory pleural effusion, and the other four were with pneumothorax. The median serum levels of PCT and WBC elevated from 0.155 to 1.470 ng/mL (P = 0.009) and from 5.920 to 10.475 × 10(9) /L (P = 0.000), respectively. No patient was given antibiotics and fever subsided. CONCLUSION: Intrapleural injection of OK-432 could increase the serum level of PCT and WBC with no bacterial infection. The serum PCT level may not be useful to distinguish whether fever was caused by the side effects of OK-432 or concurrent bacterial infection.

Pulmonary cryptococcosis in non-AIDS patients.

OBJECTIVE: To investigate the clinical features, management, and prognosis of pulmonary cryptococcosis in non-acquired immunodeficiency syndrome (AIDS) patients. METHOD: 24 cases of pulmonary cryptococcosis with accurate pathological diagnosis were retrospectively studied. RESULTS: 15 male patients and nine female patients were diagnosed at the first affiliated hospital of Sun Yat-sen University from November 1999 to November 2011. The mean age at the time of diagnosis was 44.2±11.3 years (range: 24 to 65 years). Among these patients, 13 had other comorbidities. 15 were symptomatic and the other nine were asymptomatic. The most common presenting symptoms were cough, chest tightness, expectoration, and fever. None had concurrent cryptococcal meningitis. The most frequent radiologic abnormalities on chest computed tomography (CT) scans were solitary or multiple pulmonary nodules, and masses or consolidations, and most lesions were located in the lower lobes. All patients had biopsies for the accurate diagnosis. Among the 24 patients, nine patients underwent surgical resections (eight had pneumonectomy via thoracotomy and one had a pneumonectomy via thoracoscopy). Five of the patients who underwent surgery also received antifungal drug therapy (fluconazole) for one to three months after the surgery. The other 15 only received antifungal drug therapy (fluconazole or voriconazole) for three to six months (five patients are still on therapy). The follow-up observation of 19 patients who had already finished their treatments lasted from two to 11 years, and there was no relapse, dissemination, or death in any of these patients. CONCLUSION: Non-AIDS patients with pulmonary cryptococcosis have a good prognosis with appropriate management.