On dynamical tunneling and classical resonances

This work establishes a firm relationship between classical nonlinear resonances and the phenomenon of dynamical tunneling. It is shown that the classical phase space with its hierarchy of resonance islands completely characterizes dynamical tunneling and explicit forms of the dynamical barriers can be obtained only by identifying the key resonances. Relationship between the phase space viewpoint and the quantum mechanical superexchange approach is discussed in near-integrable and mixed regular-chaotic situations. For near-integrable systems with sufficient anharmonicity the effect of multiple resonances, i.e., resonance-assisted tunneling, can be incorporated approximately. It is also argued that the presumed relation of avoided crossings to nonlinear resonances does not have to be invoked in order to understand dynamical tunneling. For molecules with low density of states the resonance-assisted mechanism is expected to be dominant.     

Synthesis of 8-substituted naphtho[2,1-b]thiophenes with cationic side chains at position 4

A series of five 8-substituted α-[bis(2-hydroxyethyi)aminoethyl]naphtho[2,1-b]thiophenes 7 and a series of seven N-(3-dimethylaminopropyl)-8-substituted naphtho[2,1-b]thiophene-4-carboxamides 8 have been synthesized. The naphtho[2,1-b]thiophene-4-carboxylic acids 4 were prepared by photooxidative cyclization of α-(2-thienyi)-β-arylacrylic acids 3. The carboxylic acids 4 were converted by a conventional five step route involving α-bromoketone intermediates to the a-[bis(2-hydroxyethyl)aminomethyl]-8-substituted naphtho-[2,1-6]thiophene-4-methanols 7 and by a standard two-step amide preparation to the N-(3-dimethylaminopropyl)-8-substituted naphtho[2,1-6]thiophene-4-carboxamides 8 .     

A convergent approach for the total synthesis of the α-glucosidase inhibitor (−)-panaxjapyne-C

The stereoselective total synthesis of (?)-panaxjapyne-C was accomplished in a convergent fashion. The synthesis utilizes the readily available enantiomers l-(+)-diethyltartrate and d-(?)-diethyltartrate and involves a Cadiot–Chodkiewicz coupling reaction, and an Ohira–Bestmann reaction as the key steps.     

Stereoselective total synthesis of (+)-sapinofuranone B

Two approaches for the total synthesis of (+)-sapinofuranone B have been described. The first strategy utilizes the methodology developed earlier in our group to get the chiral propargyl alcohol and the second strategy involves generation of threo-1,2-diol derivative by diastereoselective and enantioselective addition of [(Z)-γ-methoxymethoxyallyl]diisopinocampheylborane onto aldehyde and cross metathesis as the key steps.     

Bichromatically driven double well: parametric perspective of the strong field control landscape reveals the influence of chaotic states

The aim of this work is to understand the influence of chaotic states in control problems involving strong fields. Towards this end, we numerically construct and study the strong field control landscape of a bichromatically driven double well. A novel measure based on correlating the overlap intensities between Floquet states and an initial phase space coherent state with the parametric motion of the quasienergies is used to construct and interpret the landscape features. "Walls" of no control, which are robust under variations of the relative phase between the fields, are seen on the control landscape and associated with multilevel interactions involving chaotic Floquet states.     

Mixed integer formulation to minimize makespan in a flow shop with batch processing machines

Batch processing machines are commonly used in wafer fabrication, kilns, and chambers used for environmental stress screening (ESS). This paper proposes two models to schedule batches of jobs on two machines in a flow shop. A set of jobs with known processing times and sizes has to be grouped, to form batches, in order to be processed on the batch processing machines. The jobs are nonidentical in size. The processing time of a batch is the longest processing time of all the jobs in that batch. Mixed integer formulations are proposed for the flow shop problem when the buffer capacity is unlimited or zero. Numerical examples are presented to demonstrate the application of our model.     

Efficient Synthesis of Olmesartan Medoxomil,an Antihypertensive Drug

This document describes a simple and robust process for the synthesis of olmesartan medoxomil. This tailored process allows us to synthesize olmesartan medoxomil on a large scale with 50% overall yield. Also, our process has excellent control of the impurity profile in all the stages.     

NbCl5 mediated deprotection of methoxy methyl ether

An efficient cleavage of methoxy methyl ether using NbCl₅ is described. This protocol works efficiently with MOM ethers of alkyl, allyl, propargyl, benzyl alcohol and phenol derivatives. MOM esters are also found to be effectively cleaved under the present conditions.     

A concise stereoselective total synthesis of (+)-artemisinin

A protective group free, concise, and stereoselective total synthesis of (+)-artemisinin, starting from readily available (R)-(+)-citronellal, is described. Asymmetric 1, 4-addition, Aldol condensation, Ene reaction, regioselective hydroboration are the key steps involved in the total synthesis of the target molecule.