Intermolecular coupling Intramolecular addition

We have described our most recent efforts to calculate vibrational line shapes for liquid water and its isotopic variants under ambient conditions, as well as to calculate ultrafast observables capable of shedding light on spectral diffusion dynamics, and we have endeavored to interpret line shapes and spectral diffusion in terms of hydrogen bonding in the liquid. Our approach uses conventional classical effective two-body simulation potentials, coupled with more sophisticated quantum chemistry-based techniques for obtaining transition frequencies, transition dipoles and polarizabilities, and intramolecular and intermolecular couplings. In addition, we have used the recently developed time-averaging approximation to calculate Raman and IR line shapes for H20 (which involves... 

Herein we present calculations [6] for liquid H20 that are similar in spirit but different in detail from those of Buch [71, 110] and Torii [97]. The MD simulations are of the SPC/E model [135]. Local-mode anharmonic frequencies are generated from our most recent map developed for the H0D/D20 system [98], as are our transition dipoles. The relatively small intramolecular coupling fluctuates with molecular environment, and is determined by a separate map parameterized from ab initio calculations on clusters. The form of the intermolecular couplings is transition dipole, which is tested and parameterized from additional ab initio calculations. The effects of motional narrowing are taken into account approximately with the TAA [99]. 

In these reactions, the nitrogen nucleophile is typically an amide, carbamate, or sulfonamide. Because of the low nucleophilicity of such nitrogen functions, no intermolecular 1,4-addition involving C—N bond formation is known. In all cases reported, the carbon-nitrogen coupling takes place in an intramolecular aminopalladation. 

Samarium diiodide has also been used for the intramolecular coupling of aldehydes and ketones with O-benzyl formaldoxime [83], for the corresponding intermolecular coupling with diphenylhydrazone [84,85] and for the intramolecular coupling of an a,p-unsaturated ester with an oxime ether [86] (Scheme 39). In all these cases the addition of HMPA was found to be essential for a successful reaction. 

Intermolecular couplings involving aldehydes, terminal alkynes, and organoz-incs also proceeded with high levels of chemo- and regioselectivity (Scheme 8.15). However, unlike intramolecular couplings, direct addition of more reactive... 

Another potentially powerfnl sequence arises by combining one or two intramolecular Heck-type couplings with an intra- or intermolecular Diels-Alder addition (for early examples of inter-intermolecular one-pot domino Heck-Diels-Alder reactions see Refs. [49] and [50]). An all-intramolecular version of such a sequence has been shown to proceed reasonably smoothly for terminally alkoxycarbonyl-substituted 2-bromotrideca-l,ll-dien-6-ynes under palladium catalysis at 130 °C. At 80 °C, the sequential reaction stops after the two consecutive Heck-type cyclizations and subsequent /3-hydride elimination to give a 1,3,6-triene apparently only the ( )-isomer undergoes the intramolecular Diels-Alder reaction, as the (Z)-l,3,6-triene is observed accompanying the tetracyclic system obtained at 130 °C (Scheme 36). 

In spite of cyclo-shaped brushes being in the majority, a small portion of linear cylinders coexisted the reason for this was that the ring closure reaction is not 100%, and the linear backbone remains. In addition, not only intramolecular but also intermolecular coupling reactions take place. 

The intermolecular coupling of homoallyl alcohols with o-bromoacetophenone (181) or o-bromostyryl ketones 183 gave dihydro-182 and tetrahydronaphthalene derivatives 184 in a sequence of the Heck and aldol or the Heck and Michael reactions (Scheme 8.43 and Scheme 8.44) [350]. After addition of the initially formed arylpalladium species to the homoallyl alcohols, ehmination/isomerization yield carbonyl compounds that, under the reaction conditions, undergo intramolecular aldol reactions or Michael additions. 

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