
<?php
$productName = 'my product name';
$modx->setPlaceholder('productName', $productName);
?><meta name="title" content="[+productName+]" /> <title>[+productName+]</title>
Assuming you are using a snippet to dynamically create a product view on this single product detail page, just do something like this in the snippet:
<?php $productName = 'my product name'; $modx->setPlaceholder('productName', $productName); ?>
Then, in your template, simply use that placeholder:
<meta name="title" content="[+productName+]" /> <title>[+productName+]</title>