Some novel annulated pyrido[2,3-d]pyrimidines 6 and 7 were synthesized stereoselectively by intramolecular hetero Diels-Alder reactions involving 1-oxa-1,3-butadienes.

Alkyliminoacetonitrile derivatives were investigated as dienophiles in the Diels-Alder reaction. These activated imines react with dienes in intramolecular [4+2] cycloadditions to provide products with either the quinolizidine or indolizidine ring system, depending on the length of the tether connecting diene and dienophile. Quinolizidine cycloadducts are formed in good yield and with high ster...

in the present work, the regioselectivity for a series of diels–alder reactions (4 reactions) has beenstudied using hardness, electrophilicity and polarizability of products.furthermore,thermodynamicand kinetic calculations have been done. in all results predicted pararegioisomer is more favorableregioisomerinthese investigated reactions.all calculations have been done at the dft-b3lyp/6-31g(d)...

Caucasian alder is a large tree and one of the commercial species in the Caspian forests. We investigated the wound healing rate (WHR) and compared the diameter growth (DG) of 66 wounded and 66 unwounded alder trees 15 years after selected logging in these forests. The conditions of the wounds after 15 years were as follows: 56.1% had closed, 25.7% were open, and 18.2% had decayed. The mean WHR...

In the past, there has been an emphasis on conifer tree species in forestry operations in British Columbia. As a result, there is a serious lack of information regarding disease and decay problems in most hardwood tree species. This presentation reports the results of recent studies on levels of decay in natural red alder stands, and on the formation of stain in harvested alder logs. Disease pr...

BACKGROUND/AIMS Recently, new palaeoecological records supported by molecular analyses and palaeodistributional modelling have provided more comprehensive insights into plant behaviour during the last Quaternary cycle. We reviewed the migration history of species of subgenus Alnus during the last 50,000 years in Europe with a focus on (1) a general revision of Alnus history since the Last Glaci...

The first Diels-Alder cycloaddition of o-quinodimethane to SWNT has been performed under microwave irradiation.