Membered formation

Special substituents have been introduced onto the alkene in order to direct the cyclization reaction to five-membered formation. Examples of electronically biased alkenes for this purpose are vinyl chlorides,107 allylsilanes,108 allylstannanes100 and ketene thioacetals.9 The cyclization of allyl-silanes and -stannanes to the pyrrolizidine system is highly stereoselective.108-109 The chair geometry of ir-complex (102) explains this selectivity (equation 67). 

The theory and procedure described in Sections 2 and 3 above were applied to the data given for BMT2. There are three formations Formation 1 (the Bulk Longhands Farm Member), Formation 2 (the Altered Longhands Farm Member), and Formation 3 or the Fault Zone (the Faulted Longhands Farm Member). All the parameter data cited below were either extracted from or analyzed using the raw data given in the DECOVALEX m (2001) document. 

Roberts L W, Baba S 1968 Effects of proline on wound vessel member formation. Plant Cell Physiol 9 353... 

The decomposition of a glycidic ester to an aldehyde and carbon dioxide may involve the formation of a quasi six-membered ring, followed by the shift of three electron pairs ... 

Compounds containing a double or triple bond, usually activated by additional unsaturation (carbonyl, cyano, nitro, phenyl, etc.) In the ap position, add to the I 4-positions of a conjugated (buta-1 3-diene) system with the formation of a ax-membered ring. The ethylenic or acetylenic compound is known as the dieTwphile and the second reactant as the diene the product is the adduct. The addition is generally termed the Diels-Alder reaction or the diene synthesis. The product in the case of an ethylenic dienophile is a cyctohexene and in that of an acetylenic dienophile is a cyctohexa-1 4-diene. The active unsaturated portion of the dienophile, or that of the diene, or those in both, may be involved in rings the adduct is then polycyclic. 

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