Baihua Xu

Design, Synthesis, and Biological Evaluation of Deuterated C-Aryl Glycoside as a Potent and Long-Acting Renal Sodium-Dependent Glucose Cotransporter 2 Inhibitor for the Treatment of Type 2 Diabetes

SGLT2 inhibitors deuterated at sites susceptible to oxidative metabolism were found to have a slightly longer tmax and half-life (t1/2), dose-dependent increase in urinary glucose excretion (UGE) in rats, and slightly superior effects on UGE in dogs while retaining similar in vitro inhibitory activities against hSGLT2. In particular, deuterated compound 41 has the potential to be a robust long-acting antidiabetic agent.

Conformationally Constrained Spiro C-Arylglucosides as Potent and Selective Renal Sodium-Dependent Glucose Co-transporter 2 (SGLT2) Inhibitors

Diabetes is a highly prevalent modern disease with over 246 million people afflicted worldwide in 2007. A failure of glycemic homeostasis secondary to nutritional imbalance is considered to be the principle explanation for the alarming and increasing incidence of type 2 diabetes mellitus (DM2) in both developed and developing countries. Although a large number of antihyperglycemic agents have been developed to treat the disease, 63 % of DM2 patients fail to achieve the target levels of glycosylated hemoglobin (HbA1C<7 %) recommended by the American Diabetes Association, 4] and consequently these individuals are at risk of developing complications, such as accelerated cardiovascular disease, diabetic nephropathy, retinopathy and ulceration. Recently, renewed emphasis on the development of safe oral antidiabetic agents with a favorable cardiovascular profile has highlighted the attractions of inhibition of renal glucose resorption as a therapeutic mechanism. Sodium glucose co-transporter 2 (SGLT2) is a 672-amino acid, high-capacity, low-affinity transporter expressed nearly exclusively in the S1 and S2 segments of the renal proximal tubule and believed to mediate the majority of renal glucose resorption from the glomerular filtrate. Because the etiology of type 2 diabetes mellitus (DM2) depends on a hypertrophic adipose reservoir, mechanisms that promote glucose disposal by urinary output are therapeutically attractive compared to mechanisms that promote increased glucose assimilation by adipocytes. Selective inhibitors of SGLT2 are expected to be safe because individuals homozygous or compound heterozygous for mutations in SLC5A2, the gene encoding SGLT2, exhibit no significant morbidities. In contrast, penetrant alleles leading to SGLT1 deficiency are the genetic cause of glucose– galactose malabsorption syndrome, which is associated with severe neonatal diarrhea and failure to thrive. In particular, the high selectivity could potentially reduce the gastrointestinal side effect. Hence inhibitors selective for SGLT2 over SGLT1 are attractive candidates for development. Following the initial disclosure of T-1095A, a selective and potent SGLT2 inhibitor designed based on the naturally occurring inhibitor phlorizin, by Tanabe Seiyaku Co., Ltd. (Osaka, Japan), multiple classes of SGLT2 inhibitors have been reported, including Oand C-glucosides. The most advanced inhibitors currently undergoing clinical development in phase III trials, dapagliflozin (1) 16] and canagliflozin, are C-arylglucosides. The studies described here were directed at identifying metabolically robust agents with high selectivity towards SGLT2. Information gained from modeling studies and analysis of the crystal structure of dapagliflozin (1) suggested the possibility of creating novel and conformationally constrained chemotypes with improved potency for SGLT2 by cyclizing the 1and 6’-positions of the glucose moiety and glucose-proximal phenyl ring (Figure 1). Preliminary studies showed that retention of a chlorine substituent at the 4’-position on the proximal phenyl ring is critical for activity. The synthesis and evaluation of three series of novel analogues, which have a different scaffold than previously reported inhibitors, are described here. The synthesis of spiro[isobenzofuran-1,2’-pyran] analogues 12 a–e was addressed first (Scheme 1). Persilylated gluconolactone 3 was prepared in 89 % yield by the slow addition of trimethylsilyl chloride (TMSCl) to commercially available gluconolactone 2 in the presence of N-methylmorpholine. 21] Benzoic acid 4 was subjected to bromination with N-bromosuccinimide (NBS) followed by esterification to yield aniline 6. Sandmeyer reaction and subsequent oxidation of 7 provided the key electron-deficient tetra-substituted benzene 8. Friedel–Crafts acylation of R substituted benzenes generated the benzophenone 9. Selective reduction of the resulting ketone with triethylsilane and further reduction of the methyl ester gave the corresponding benzyl alcohol 10. Protection of the primary hydroxy group with chloromethyl methyl ether produced bromide 11. Lithium–halogen exchange and subsequent coupling with lactone 3 gave a mixture of lactols, which were converted in situ to the desired spiro[isobenzofuran-1,2’-pyran] derivatives 12 a–e in 40 to 63 % yield after purification by preparative thin layer chromatography (TLC). The synthesis of spiro[indane-1,2’-pyran] glucosides 19 a–e was more challenging than that of O-spiroketal C-arylglucosides analogues (Scheme 2). Benzyl alcohol 13 was oxidized with Dess–Martin reagent and subsequently subjected to [a] B. Lv, B. Xu, Prof. Dr. Y. Chen Chengdu Institute of Organic Chemistry (CIOC) Chinese Academy of Sciences (CAS) No. 16, Southion 2, the first circle road, 610041 Chengdu (P.R. China) Fax: (+ 86) 28-8525-9387 E-mail : 51popo51@163.com chenyw@cioc.ac.cn [b] B. Lv, Dr. Y. Feng, Dr. J. Dong, Dr. M. Xu, B. Xu, W. Zhang, Dr. Z. Sheng, Prof. Dr. Y. Chen Egret Pharma (Shanghai) Company, Ltd. Halei Road 1118, 201203 Shanghai (P.R. China) [c] Dr. A. Welihinda, Prof. Dr. B. Seed Theracos Inc. , 550 Del Rey Avenue, Sunnyvale, CA 94805-3528 (USA) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cmdc.201000051.

ortho-Substituted C-aryl glucosides as highly potent and selective renal sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors

A series of 2-substituted C-aryl glucosides have been synthesized and evaluated for inhibition of hSGLT1 and hSGLT2. Introduction of an appropriate ortho substituent at the proximal phenyl ring adjacent to the glycosidic bond was found to improve SGLT2 inhibitory activity and dramatically increase selectivity for hSGLT2 over hSGLT1. Selected compounds were investigated for in vivo efficacy.