Synthetic Studies to Lyngbouilloside: A Phosphate Tether-Mediated Synthesis of the Macrolactone Core

A concise synthetic pathway to the originally assigned structure of lyngbouilloside macrolactone (3) is reported. The core macrocycle 3 was synthesized via a phosphate tether-mediated, one-pot, sequential RCM/CM/chemoselective hydrogenation reaction, Roskamp homologation, and a high yielding Boeckman acylketene cyclization

Phototherapy induced hypocalcemia in neonates: A case

Objective: The objective of the study was to evaluate the adverse effects of phototherapy both total and ionic calcium levels in neonates. Methods: A case–control prospective study was conducted in the Department of Pediatrics, over a period of 15 months. All neonates preterm or term with icterus in phototherapy range formed the study group(s). Serum calcium total and ionized were measured on a serial basis. Results: Neonates in the study group had significant fall in total serum calcium after phototherapy (0.94±0.49 mg/dl). Similarly, ionized serum calcium also decreased after phototherapy in study group (0.56±0.36 mg/dl), p<0.001 statistically significant. The overall incidence of hypocalcemia was 9.6%, higher in preterm (11.7%) than term (8.5%) neonates. Jitteriness and irritability both were seen in 25% of the neonates. None of the neonate had convulsion, but it may occur if the level falls further. Conclusions: While giving phototherapy to a premature baby or a sick baby we should monitor serum calcium levels. Prophylactically oral supplementation of calcium may be considered in newborns receiving phototherapy as it induces hypocalcemia

Phosphate Tether-Mediated Approach to the Formal Total Synthesis of (-)-Salicylihalamides A and B

A concise formal synthesis of the cytotoxic macrolides (-)-salicylihalamides A and B is reported. Key features of the synthetic strategy include a chemoselective hydroboration, highly regio- and diastereoselective methyl cuprate addition, Pd-catalyzed formate reduction, and an E-selective ring-closing metathesis to construct the 12-membered macrocycle subunit. Overall, two routes have been developed from a readily prepared bicyclic phosphate (4-steps), a 13-step route and a more efficient 9-step sequence relying on regioselective esterification of a key diol

Phosphate Tether-Mediated Ring-Closing Metathesis Studies to Complex 1,3-anti-Diol-Containing Subunits

This is the peer reviewed version of the following article: Chegondi, R., Maitra, S., Markley, J. L., & Hanson, P. R. (2013). Phosphate Tether-Mediated Ring-Closing Metathesis Studies to Complex 1,3-anti-Diol-Containing Subunits. Chemistry (Weinheim an Der Bergstrasse, Germany), 19(25), 10.1002/chem.201300913. http://doi.org/10.1002/chem.201300913, which has been published in final form at doi.org/10.1002/chem.201300913. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.An array of examples of diastereoselective, phosphate tether-mediated ring-closing metathesis reactions, which highlight the importance of product ring size and substrate stereochemical compatibility, as well as complexity, is reported. Studies focus primarily on the formation of bicyclo[n.3.1]phosphates, involving the coupling of C2-symmetric dienediol subunits with a variety of simple, as well as complex alcohol cross-partners

Phosphate Tether-Mediated Ring-Closing Metathesis for the Generation of Medium to Large, P-Stereogenic Bicyclo[n.3.1]phosphates

A phosphate tether-mediated ring-closing metathesis study towards the synthesis of P-stereogenic bicyclo[6.3.1]-, bicyclo[7.3.1]-, and bicyclo[8.3.1]phosphates is reported. This study demonstrates expanded utility of phosphate tether-mediated desymmetrization of C2-symmetric, 1,3-anti-diol dienes in generating complex medium to large, P-stereogenic bicyclo[n.3.1]phosphates.

A Concise, Phosphate-Mediated Approach to the Total Synthesis of (−)-Tetrahydrolipstatin

An efficient synthesis of (−)-tetrahydrolipstatin (THL) is reported. This method takes advantage of a phosphate tether-mediated, one-pot, sequential RCM/CM/hydrogenation protocol to deliver THL in 8 total steps from a readily prepared (S,S)-triene. The strategy incorporates selective cross metathesis, regio-selective hydrogenation, regio- and diastereoselective cuprate addition and Mitsunobu inversion for installation of the C5 formamide ester subunit

A Phosphate Tether-Mediated, One-pot, Sequential RCM/CM/Chemo-selective Hydrogenation Protocol

A versatile three-step, one-pot, sequential reaction protocol involving RCM, CM, and chemoselective hydrogenation is reported. This phosphate tether-mediated process occurs without intermediate isolation, is chemoselective and is governed by stereoelectronic properties innate to phosphate tethers, which ultimately act to preserve the integrity of the bisallylic, bicyclic phosphate for subsequent nucleophilic additions. Overall, this process can be used to efficiently generate advanced polyol synthons

Total Synthesis of Dolabelide C: A Phosphate-Mediated Approach

The first synthesis of dolabelide C (1), a cytotoxic marine macrolide, is reported utilizing a phosphate tether-mediated approach. Bicyclic phosphates (S,S,SP)-5 and (R,R,RP)-5 serve as the central building blocks for the construction of two major 1,3-anti-diol subunits in 1 through selective cleavage pathways, regioselective olefin reduction and cross-metathesis. Overall, phosphate-mediated processes provided copious amounts of both major subunits allowing for a detailed RCM macrocyclization study to the 24-membered macrolactone 1

Theories of Ultrasonic Velocities and their Application in Binary Liquid Mixtures of N-Ethylaniline with Some Toluenes (Toluene, o-Nitrotoluene and m-Nitrotoluene)

Abstract: Ultrasonic velocities and densities of the binary liquid mixtures of N-ethyl aniline with different toluenes like toluene, o-nitrotoluene and m-nitrotoluene have been measured at temperatures 303.15 and 308.15 K over the entire composition range. Various theories of ultrasonic velocity were applied to experimental values in evaluating the velocities using Nomoto's relation (U NR ), Impedence relation (U IR ), Ideal mixing relation (U IMR ), Jungie's relation (U JR )and Rao's specific velocity relation (U R ). The molecular interaction parameter (χ) has been evaluated from the values of experimental and theoretical velocities. The variation of this interaction parameter with the composition mixture has been discussed in terms of molecular interactions